diff --git a/vendor/golang.org/x/text/language/coverage.go b/vendor/golang.org/x/text/language/coverage.go
new file mode 100644
index 0000000..a24fd1a
--- /dev/null
+++ b/vendor/golang.org/x/text/language/coverage.go
@@ -0,0 +1,187 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package language
+
+import (
+	"fmt"
+	"sort"
+
+	"golang.org/x/text/internal/language"
+)
+
+// The Coverage interface is used to define the level of coverage of an
+// internationalization service. Note that not all types are supported by all
+// services. As lists may be generated on the fly, it is recommended that users
+// of a Coverage cache the results.
+type Coverage interface {
+	// Tags returns the list of supported tags.
+	Tags() []Tag
+
+	// BaseLanguages returns the list of supported base languages.
+	BaseLanguages() []Base
+
+	// Scripts returns the list of supported scripts.
+	Scripts() []Script
+
+	// Regions returns the list of supported regions.
+	Regions() []Region
+}
+
+var (
+	// Supported defines a Coverage that lists all supported subtags. Tags
+	// always returns nil.
+	Supported Coverage = allSubtags{}
+)
+
+// TODO:
+// - Support Variants, numbering systems.
+// - CLDR coverage levels.
+// - Set of common tags defined in this package.
+
+type allSubtags struct{}
+
+// Regions returns the list of supported regions. As all regions are in a
+// consecutive range, it simply returns a slice of numbers in increasing order.
+// The "undefined" region is not returned.
+func (s allSubtags) Regions() []Region {
+	reg := make([]Region, language.NumRegions)
+	for i := range reg {
+		reg[i] = Region{language.Region(i + 1)}
+	}
+	return reg
+}
+
+// Scripts returns the list of supported scripts. As all scripts are in a
+// consecutive range, it simply returns a slice of numbers in increasing order.
+// The "undefined" script is not returned.
+func (s allSubtags) Scripts() []Script {
+	scr := make([]Script, language.NumScripts)
+	for i := range scr {
+		scr[i] = Script{language.Script(i + 1)}
+	}
+	return scr
+}
+
+// BaseLanguages returns the list of all supported base languages. It generates
+// the list by traversing the internal structures.
+func (s allSubtags) BaseLanguages() []Base {
+	bs := language.BaseLanguages()
+	base := make([]Base, len(bs))
+	for i, b := range bs {
+		base[i] = Base{b}
+	}
+	return base
+}
+
+// Tags always returns nil.
+func (s allSubtags) Tags() []Tag {
+	return nil
+}
+
+// coverage is used by NewCoverage which is used as a convenient way for
+// creating Coverage implementations for partially defined data. Very often a
+// package will only need to define a subset of slices. coverage provides a
+// convenient way to do this. Moreover, packages using NewCoverage, instead of
+// their own implementation, will not break if later new slice types are added.
+type coverage struct {
+	tags    func() []Tag
+	bases   func() []Base
+	scripts func() []Script
+	regions func() []Region
+}
+
+func (s *coverage) Tags() []Tag {
+	if s.tags == nil {
+		return nil
+	}
+	return s.tags()
+}
+
+// bases implements sort.Interface and is used to sort base languages.
+type bases []Base
+
+func (b bases) Len() int {
+	return len(b)
+}
+
+func (b bases) Swap(i, j int) {
+	b[i], b[j] = b[j], b[i]
+}
+
+func (b bases) Less(i, j int) bool {
+	return b[i].langID < b[j].langID
+}
+
+// BaseLanguages returns the result from calling s.bases if it is specified or
+// otherwise derives the set of supported base languages from tags.
+func (s *coverage) BaseLanguages() []Base {
+	if s.bases == nil {
+		tags := s.Tags()
+		if len(tags) == 0 {
+			return nil
+		}
+		a := make([]Base, len(tags))
+		for i, t := range tags {
+			a[i] = Base{language.Language(t.lang())}
+		}
+		sort.Sort(bases(a))
+		k := 0
+		for i := 1; i < len(a); i++ {
+			if a[k] != a[i] {
+				k++
+				a[k] = a[i]
+			}
+		}
+		return a[:k+1]
+	}
+	return s.bases()
+}
+
+func (s *coverage) Scripts() []Script {
+	if s.scripts == nil {
+		return nil
+	}
+	return s.scripts()
+}
+
+func (s *coverage) Regions() []Region {
+	if s.regions == nil {
+		return nil
+	}
+	return s.regions()
+}
+
+// NewCoverage returns a Coverage for the given lists. It is typically used by
+// packages providing internationalization services to define their level of
+// coverage. A list may be of type []T or func() []T, where T is either Tag,
+// Base, Script or Region. The returned Coverage derives the value for Bases
+// from Tags if no func or slice for []Base is specified. For other unspecified
+// types the returned Coverage will return nil for the respective methods.
+func NewCoverage(list ...interface{}) Coverage {
+	s := &coverage{}
+	for _, x := range list {
+		switch v := x.(type) {
+		case func() []Base:
+			s.bases = v
+		case func() []Script:
+			s.scripts = v
+		case func() []Region:
+			s.regions = v
+		case func() []Tag:
+			s.tags = v
+		case []Base:
+			s.bases = func() []Base { return v }
+		case []Script:
+			s.scripts = func() []Script { return v }
+		case []Region:
+			s.regions = func() []Region { return v }
+		case []Tag:
+			s.tags = func() []Tag { return v }
+		default:
+			panic(fmt.Sprintf("language: unsupported set type %T", v))
+		}
+	}
+	return s
+}
diff --git a/vendor/golang.org/x/text/language/doc.go b/vendor/golang.org/x/text/language/doc.go
new file mode 100644
index 0000000..8afecd5
--- /dev/null
+++ b/vendor/golang.org/x/text/language/doc.go
@@ -0,0 +1,102 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package language implements BCP 47 language tags and related functionality.
+//
+// The most important function of package language is to match a list of
+// user-preferred languages to a list of supported languages.
+// It alleviates the developer of dealing with the complexity of this process
+// and provides the user with the best experience
+// (see https://blog.golang.org/matchlang).
+//
+//
+// Matching preferred against supported languages
+//
+// A Matcher for an application that supports English, Australian English,
+// Danish, and standard Mandarin can be created as follows:
+//
+//    var matcher = language.NewMatcher([]language.Tag{
+//        language.English,   // The first language is used as fallback.
+//        language.MustParse("en-AU"),
+//        language.Danish,
+//        language.Chinese,
+//    })
+//
+// This list of supported languages is typically implied by the languages for
+// which there exists translations of the user interface.
+//
+// User-preferred languages usually come as a comma-separated list of BCP 47
+// language tags.
+// The MatchString finds best matches for such strings:
+//
+//    handler(w http.ResponseWriter, r *http.Request) {
+//        lang, _ := r.Cookie("lang")
+//        accept := r.Header.Get("Accept-Language")
+//        tag, _ := language.MatchStrings(matcher, lang.String(), accept)
+//
+//        // tag should now be used for the initialization of any
+//        // locale-specific service.
+//    }
+//
+// The Matcher's Match method can be used to match Tags directly.
+//
+// Matchers are aware of the intricacies of equivalence between languages, such
+// as deprecated subtags, legacy tags, macro languages, mutual
+// intelligibility between scripts and languages, and transparently passing
+// BCP 47 user configuration.
+// For instance, it will know that a reader of Bokmål Danish can read Norwegian
+// and will know that Cantonese ("yue") is a good match for "zh-HK".
+//
+//
+// Using match results
+//
+// To guarantee a consistent user experience to the user it is important to
+// use the same language tag for the selection of any locale-specific services.
+// For example, it is utterly confusing to substitute spelled-out numbers
+// or dates in one language in text of another language.
+// More subtly confusing is using the wrong sorting order or casing
+// algorithm for a certain language.
+//
+//    All the packages in x/text that provide locale-specific services
+//    (e.g. collate, cases) should be initialized with the tag that was
+//    obtained at the start of an interaction with the user.
+//
+// Note that Tag that is returned by Match and MatchString may differ from any
+// of the supported languages, as it may contain carried over settings from
+// the user tags.
+// This may be inconvenient when your application has some additional
+// locale-specific data for your supported languages.
+// Match and MatchString both return the index of the matched supported tag
+// to simplify associating such data with the matched tag.
+//
+//
+// Canonicalization
+//
+// If one uses the Matcher to compare languages one does not need to
+// worry about canonicalization.
+//
+// The meaning of a Tag varies per application. The language package
+// therefore delays canonicalization and preserves information as much
+// as possible. The Matcher, however, will always take into account that
+// two different tags may represent the same language.
+//
+// By default, only legacy and deprecated tags are converted into their
+// canonical equivalent. All other information is preserved. This approach makes
+// the confidence scores more accurate and allows matchers to distinguish
+// between variants that are otherwise lost.
+//
+// As a consequence, two tags that should be treated as identical according to
+// BCP 47 or CLDR, like "en-Latn" and "en", will be represented differently. The
+// Matcher handles such distinctions, though, and is aware of the
+// equivalence relations. The CanonType type can be used to alter the
+// canonicalization form.
+//
+// References
+//
+// BCP 47 - Tags for Identifying Languages http://tools.ietf.org/html/bcp47
+//
+package language // import "golang.org/x/text/language"
+
+// TODO: explanation on how to match languages for your own locale-specific
+// service.
diff --git a/vendor/golang.org/x/text/language/gen.go b/vendor/golang.org/x/text/language/gen.go
new file mode 100644
index 0000000..3004eb4
--- /dev/null
+++ b/vendor/golang.org/x/text/language/gen.go
@@ -0,0 +1,305 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ignore
+
+// Language tag table generator.
+// Data read from the web.
+
+package main
+
+import (
+	"flag"
+	"fmt"
+	"io"
+	"log"
+	"sort"
+	"strconv"
+	"strings"
+
+	"golang.org/x/text/internal/gen"
+	"golang.org/x/text/internal/language"
+	"golang.org/x/text/unicode/cldr"
+)
+
+var (
+	test = flag.Bool("test",
+		false,
+		"test existing tables; can be used to compare web data with package data.")
+	outputFile = flag.String("output",
+		"tables.go",
+		"output file for generated tables")
+)
+
+func main() {
+	gen.Init()
+
+	w := gen.NewCodeWriter()
+	defer w.WriteGoFile("tables.go", "language")
+
+	b := newBuilder(w)
+	gen.WriteCLDRVersion(w)
+
+	b.writeConstants()
+	b.writeMatchData()
+}
+
+type builder struct {
+	w    *gen.CodeWriter
+	hw   io.Writer // MultiWriter for w and w.Hash
+	data *cldr.CLDR
+	supp *cldr.SupplementalData
+}
+
+func (b *builder) langIndex(s string) uint16 {
+	return uint16(language.MustParseBase(s))
+}
+
+func (b *builder) regionIndex(s string) int {
+	return int(language.MustParseRegion(s))
+}
+
+func (b *builder) scriptIndex(s string) int {
+	return int(language.MustParseScript(s))
+}
+
+func newBuilder(w *gen.CodeWriter) *builder {
+	r := gen.OpenCLDRCoreZip()
+	defer r.Close()
+	d := &cldr.Decoder{}
+	data, err := d.DecodeZip(r)
+	if err != nil {
+		log.Fatal(err)
+	}
+	b := builder{
+		w:    w,
+		hw:   io.MultiWriter(w, w.Hash),
+		data: data,
+		supp: data.Supplemental(),
+	}
+	return &b
+}
+
+// writeConsts computes f(v) for all v in values and writes the results
+// as constants named _v to a single constant block.
+func (b *builder) writeConsts(f func(string) int, values ...string) {
+	fmt.Fprintln(b.w, "const (")
+	for _, v := range values {
+		fmt.Fprintf(b.w, "\t_%s = %v\n", v, f(v))
+	}
+	fmt.Fprintln(b.w, ")")
+}
+
+// TODO: region inclusion data will probably not be use used in future matchers.
+
+var langConsts = []string{
+	"de", "en", "fr", "it", "mo", "no", "nb", "pt", "sh", "mul", "und",
+}
+
+var scriptConsts = []string{
+	"Latn", "Hani", "Hans", "Hant", "Qaaa", "Qaai", "Qabx", "Zinh", "Zyyy",
+	"Zzzz",
+}
+
+var regionConsts = []string{
+	"001", "419", "BR", "CA", "ES", "GB", "MD", "PT", "UK", "US",
+	"ZZ", "XA", "XC", "XK", // Unofficial tag for Kosovo.
+}
+
+func (b *builder) writeConstants() {
+	b.writeConsts(func(s string) int { return int(b.langIndex(s)) }, langConsts...)
+	b.writeConsts(b.regionIndex, regionConsts...)
+	b.writeConsts(b.scriptIndex, scriptConsts...)
+}
+
+type mutualIntelligibility struct {
+	want, have uint16
+	distance   uint8
+	oneway     bool
+}
+
+type scriptIntelligibility struct {
+	wantLang, haveLang     uint16
+	wantScript, haveScript uint8
+	distance               uint8
+	// Always oneway
+}
+
+type regionIntelligibility struct {
+	lang     uint16 // compact language id
+	script   uint8  // 0 means any
+	group    uint8  // 0 means any; if bit 7 is set it means inverse
+	distance uint8
+	// Always twoway.
+}
+
+// writeMatchData writes tables with languages and scripts for which there is
+// mutual intelligibility. The data is based on CLDR's languageMatching data.
+// Note that we use a different algorithm than the one defined by CLDR and that
+// we slightly modify the data. For example, we convert scores to confidence levels.
+// We also drop all region-related data as we use a different algorithm to
+// determine region equivalence.
+func (b *builder) writeMatchData() {
+	lm := b.supp.LanguageMatching.LanguageMatches
+	cldr.MakeSlice(&lm).SelectAnyOf("type", "written_new")
+
+	regionHierarchy := map[string][]string{}
+	for _, g := range b.supp.TerritoryContainment.Group {
+		regions := strings.Split(g.Contains, " ")
+		regionHierarchy[g.Type] = append(regionHierarchy[g.Type], regions...)
+	}
+	regionToGroups := make([]uint8, language.NumRegions)
+
+	idToIndex := map[string]uint8{}
+	for i, mv := range lm[0].MatchVariable {
+		if i > 6 {
+			log.Fatalf("Too many groups: %d", i)
+		}
+		idToIndex[mv.Id] = uint8(i + 1)
+		// TODO: also handle '-'
+		for _, r := range strings.Split(mv.Value, "+") {
+			todo := []string{r}
+			for k := 0; k < len(todo); k++ {
+				r := todo[k]
+				regionToGroups[b.regionIndex(r)] |= 1 << uint8(i)
+				todo = append(todo, regionHierarchy[r]...)
+			}
+		}
+	}
+	b.w.WriteVar("regionToGroups", regionToGroups)
+
+	// maps language id to in- and out-of-group region.
+	paradigmLocales := [][3]uint16{}
+	locales := strings.Split(lm[0].ParadigmLocales[0].Locales, " ")
+	for i := 0; i < len(locales); i += 2 {
+		x := [3]uint16{}
+		for j := 0; j < 2; j++ {
+			pc := strings.SplitN(locales[i+j], "-", 2)
+			x[0] = b.langIndex(pc[0])
+			if len(pc) == 2 {
+				x[1+j] = uint16(b.regionIndex(pc[1]))
+			}
+		}
+		paradigmLocales = append(paradigmLocales, x)
+	}
+	b.w.WriteVar("paradigmLocales", paradigmLocales)
+
+	b.w.WriteType(mutualIntelligibility{})
+	b.w.WriteType(scriptIntelligibility{})
+	b.w.WriteType(regionIntelligibility{})
+
+	matchLang := []mutualIntelligibility{}
+	matchScript := []scriptIntelligibility{}
+	matchRegion := []regionIntelligibility{}
+	// Convert the languageMatch entries in lists keyed by desired language.
+	for _, m := range lm[0].LanguageMatch {
+		// Different versions of CLDR use different separators.
+		desired := strings.Replace(m.Desired, "-", "_", -1)
+		supported := strings.Replace(m.Supported, "-", "_", -1)
+		d := strings.Split(desired, "_")
+		s := strings.Split(supported, "_")
+		if len(d) != len(s) {
+			log.Fatalf("not supported: desired=%q; supported=%q", desired, supported)
+			continue
+		}
+		distance, _ := strconv.ParseInt(m.Distance, 10, 8)
+		switch len(d) {
+		case 2:
+			if desired == supported && desired == "*_*" {
+				continue
+			}
+			// language-script pair.
+			matchScript = append(matchScript, scriptIntelligibility{
+				wantLang:   uint16(b.langIndex(d[0])),
+				haveLang:   uint16(b.langIndex(s[0])),
+				wantScript: uint8(b.scriptIndex(d[1])),
+				haveScript: uint8(b.scriptIndex(s[1])),
+				distance:   uint8(distance),
+			})
+			if m.Oneway != "true" {
+				matchScript = append(matchScript, scriptIntelligibility{
+					wantLang:   uint16(b.langIndex(s[0])),
+					haveLang:   uint16(b.langIndex(d[0])),
+					wantScript: uint8(b.scriptIndex(s[1])),
+					haveScript: uint8(b.scriptIndex(d[1])),
+					distance:   uint8(distance),
+				})
+			}
+		case 1:
+			if desired == supported && desired == "*" {
+				continue
+			}
+			if distance == 1 {
+				// nb == no is already handled by macro mapping. Check there
+				// really is only this case.
+				if d[0] != "no" || s[0] != "nb" {
+					log.Fatalf("unhandled equivalence %s == %s", s[0], d[0])
+				}
+				continue
+			}
+			// TODO: consider dropping oneway field and just doubling the entry.
+			matchLang = append(matchLang, mutualIntelligibility{
+				want:     uint16(b.langIndex(d[0])),
+				have:     uint16(b.langIndex(s[0])),
+				distance: uint8(distance),
+				oneway:   m.Oneway == "true",
+			})
+		case 3:
+			if desired == supported && desired == "*_*_*" {
+				continue
+			}
+			if desired != supported {
+				// This is now supported by CLDR, but only one case, which
+				// should already be covered by paradigm locales. For instance,
+				// test case "und, en, en-GU, en-IN, en-GB ; en-ZA ; en-GB" in
+				// testdata/CLDRLocaleMatcherTest.txt tests this.
+				if supported != "en_*_GB" {
+					log.Fatalf("not supported: desired=%q; supported=%q", desired, supported)
+				}
+				continue
+			}
+			ri := regionIntelligibility{
+				lang:     b.langIndex(d[0]),
+				distance: uint8(distance),
+			}
+			if d[1] != "*" {
+				ri.script = uint8(b.scriptIndex(d[1]))
+			}
+			switch {
+			case d[2] == "*":
+				ri.group = 0x80 // not contained in anything
+			case strings.HasPrefix(d[2], "$!"):
+				ri.group = 0x80
+				d[2] = "$" + d[2][len("$!"):]
+				fallthrough
+			case strings.HasPrefix(d[2], "$"):
+				ri.group |= idToIndex[d[2]]
+			}
+			matchRegion = append(matchRegion, ri)
+		default:
+			log.Fatalf("not supported: desired=%q; supported=%q", desired, supported)
+		}
+	}
+	sort.SliceStable(matchLang, func(i, j int) bool {
+		return matchLang[i].distance < matchLang[j].distance
+	})
+	b.w.WriteComment(`
+		matchLang holds pairs of langIDs of base languages that are typically
+		mutually intelligible. Each pair is associated with a confidence and
+		whether the intelligibility goes one or both ways.`)
+	b.w.WriteVar("matchLang", matchLang)
+
+	b.w.WriteComment(`
+		matchScript holds pairs of scriptIDs where readers of one script
+		can typically also read the other. Each is associated with a confidence.`)
+	sort.SliceStable(matchScript, func(i, j int) bool {
+		return matchScript[i].distance < matchScript[j].distance
+	})
+	b.w.WriteVar("matchScript", matchScript)
+
+	sort.SliceStable(matchRegion, func(i, j int) bool {
+		return matchRegion[i].distance < matchRegion[j].distance
+	})
+	b.w.WriteVar("matchRegion", matchRegion)
+}
diff --git a/vendor/golang.org/x/text/language/go1_1.go b/vendor/golang.org/x/text/language/go1_1.go
new file mode 100644
index 0000000..380f4c0
--- /dev/null
+++ b/vendor/golang.org/x/text/language/go1_1.go
@@ -0,0 +1,38 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !go1.2
+
+package language
+
+import "sort"
+
+func sortStable(s sort.Interface) {
+	ss := stableSort{
+		s:   s,
+		pos: make([]int, s.Len()),
+	}
+	for i := range ss.pos {
+		ss.pos[i] = i
+	}
+	sort.Sort(&ss)
+}
+
+type stableSort struct {
+	s   sort.Interface
+	pos []int
+}
+
+func (s *stableSort) Len() int {
+	return len(s.pos)
+}
+
+func (s *stableSort) Less(i, j int) bool {
+	return s.s.Less(i, j) || !s.s.Less(j, i) && s.pos[i] < s.pos[j]
+}
+
+func (s *stableSort) Swap(i, j int) {
+	s.s.Swap(i, j)
+	s.pos[i], s.pos[j] = s.pos[j], s.pos[i]
+}
diff --git a/vendor/golang.org/x/text/language/go1_2.go b/vendor/golang.org/x/text/language/go1_2.go
new file mode 100644
index 0000000..38268c5
--- /dev/null
+++ b/vendor/golang.org/x/text/language/go1_2.go
@@ -0,0 +1,11 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build go1.2
+
+package language
+
+import "sort"
+
+var sortStable = sort.Stable
diff --git a/vendor/golang.org/x/text/language/language.go b/vendor/golang.org/x/text/language/language.go
new file mode 100644
index 0000000..abfa17f
--- /dev/null
+++ b/vendor/golang.org/x/text/language/language.go
@@ -0,0 +1,601 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:generate go run gen.go -output tables.go
+
+package language
+
+// TODO: Remove above NOTE after:
+// - verifying that tables are dropped correctly (most notably matcher tables).
+
+import (
+	"strings"
+
+	"golang.org/x/text/internal/language"
+	"golang.org/x/text/internal/language/compact"
+)
+
+// Tag represents a BCP 47 language tag. It is used to specify an instance of a
+// specific language or locale. All language tag values are guaranteed to be
+// well-formed.
+type Tag compact.Tag
+
+func makeTag(t language.Tag) (tag Tag) {
+	return Tag(compact.Make(t))
+}
+
+func (t *Tag) tag() language.Tag {
+	return (*compact.Tag)(t).Tag()
+}
+
+func (t *Tag) isCompact() bool {
+	return (*compact.Tag)(t).IsCompact()
+}
+
+// TODO: improve performance.
+func (t *Tag) lang() language.Language { return t.tag().LangID }
+func (t *Tag) region() language.Region { return t.tag().RegionID }
+func (t *Tag) script() language.Script { return t.tag().ScriptID }
+
+// Make is a convenience wrapper for Parse that omits the error.
+// In case of an error, a sensible default is returned.
+func Make(s string) Tag {
+	return Default.Make(s)
+}
+
+// Make is a convenience wrapper for c.Parse that omits the error.
+// In case of an error, a sensible default is returned.
+func (c CanonType) Make(s string) Tag {
+	t, _ := c.Parse(s)
+	return t
+}
+
+// Raw returns the raw base language, script and region, without making an
+// attempt to infer their values.
+func (t Tag) Raw() (b Base, s Script, r Region) {
+	tt := t.tag()
+	return Base{tt.LangID}, Script{tt.ScriptID}, Region{tt.RegionID}
+}
+
+// IsRoot returns true if t is equal to language "und".
+func (t Tag) IsRoot() bool {
+	return compact.Tag(t).IsRoot()
+}
+
+// CanonType can be used to enable or disable various types of canonicalization.
+type CanonType int
+
+const (
+	// Replace deprecated base languages with their preferred replacements.
+	DeprecatedBase CanonType = 1 << iota
+	// Replace deprecated scripts with their preferred replacements.
+	DeprecatedScript
+	// Replace deprecated regions with their preferred replacements.
+	DeprecatedRegion
+	// Remove redundant scripts.
+	SuppressScript
+	// Normalize legacy encodings. This includes legacy languages defined in
+	// CLDR as well as bibliographic codes defined in ISO-639.
+	Legacy
+	// Map the dominant language of a macro language group to the macro language
+	// subtag. For example cmn -> zh.
+	Macro
+	// The CLDR flag should be used if full compatibility with CLDR is required.
+	// There are a few cases where language.Tag may differ from CLDR. To follow all
+	// of CLDR's suggestions, use All|CLDR.
+	CLDR
+
+	// Raw can be used to Compose or Parse without Canonicalization.
+	Raw CanonType = 0
+
+	// Replace all deprecated tags with their preferred replacements.
+	Deprecated = DeprecatedBase | DeprecatedScript | DeprecatedRegion
+
+	// All canonicalizations recommended by BCP 47.
+	BCP47 = Deprecated | SuppressScript
+
+	// All canonicalizations.
+	All = BCP47 | Legacy | Macro
+
+	// Default is the canonicalization used by Parse, Make and Compose. To
+	// preserve as much information as possible, canonicalizations that remove
+	// potentially valuable information are not included. The Matcher is
+	// designed to recognize similar tags that would be the same if
+	// they were canonicalized using All.
+	Default = Deprecated | Legacy
+
+	canonLang = DeprecatedBase | Legacy | Macro
+
+	// TODO: LikelyScript, LikelyRegion: suppress similar to ICU.
+)
+
+// canonicalize returns the canonicalized equivalent of the tag and
+// whether there was any change.
+func canonicalize(c CanonType, t language.Tag) (language.Tag, bool) {
+	if c == Raw {
+		return t, false
+	}
+	changed := false
+	if c&SuppressScript != 0 {
+		if t.LangID.SuppressScript() == t.ScriptID {
+			t.ScriptID = 0
+			changed = true
+		}
+	}
+	if c&canonLang != 0 {
+		for {
+			if l, aliasType := t.LangID.Canonicalize(); l != t.LangID {
+				switch aliasType {
+				case language.Legacy:
+					if c&Legacy != 0 {
+						if t.LangID == _sh && t.ScriptID == 0 {
+							t.ScriptID = _Latn
+						}
+						t.LangID = l
+						changed = true
+					}
+				case language.Macro:
+					if c&Macro != 0 {
+						// We deviate here from CLDR. The mapping "nb" -> "no"
+						// qualifies as a typical Macro language mapping.  However,
+						// for legacy reasons, CLDR maps "no", the macro language
+						// code for Norwegian, to the dominant variant "nb". This
+						// change is currently under consideration for CLDR as well.
+						// See https://unicode.org/cldr/trac/ticket/2698 and also
+						// https://unicode.org/cldr/trac/ticket/1790 for some of the
+						// practical implications. TODO: this check could be removed
+						// if CLDR adopts this change.
+						if c&CLDR == 0 || t.LangID != _nb {
+							changed = true
+							t.LangID = l
+						}
+					}
+				case language.Deprecated:
+					if c&DeprecatedBase != 0 {
+						if t.LangID == _mo && t.RegionID == 0 {
+							t.RegionID = _MD
+						}
+						t.LangID = l
+						changed = true
+						// Other canonicalization types may still apply.
+						continue
+					}
+				}
+			} else if c&Legacy != 0 && t.LangID == _no && c&CLDR != 0 {
+				t.LangID = _nb
+				changed = true
+			}
+			break
+		}
+	}
+	if c&DeprecatedScript != 0 {
+		if t.ScriptID == _Qaai {
+			changed = true
+			t.ScriptID = _Zinh
+		}
+	}
+	if c&DeprecatedRegion != 0 {
+		if r := t.RegionID.Canonicalize(); r != t.RegionID {
+			changed = true
+			t.RegionID = r
+		}
+	}
+	return t, changed
+}
+
+// Canonicalize returns the canonicalized equivalent of the tag.
+func (c CanonType) Canonicalize(t Tag) (Tag, error) {
+	// First try fast path.
+	if t.isCompact() {
+		if _, changed := canonicalize(c, compact.Tag(t).Tag()); !changed {
+			return t, nil
+		}
+	}
+	// It is unlikely that one will canonicalize a tag after matching. So do
+	// a slow but simple approach here.
+	if tag, changed := canonicalize(c, t.tag()); changed {
+		tag.RemakeString()
+		return makeTag(tag), nil
+	}
+	return t, nil
+
+}
+
+// Confidence indicates the level of certainty for a given return value.
+// For example, Serbian may be written in Cyrillic or Latin script.
+// The confidence level indicates whether a value was explicitly specified,
+// whether it is typically the only possible value, or whether there is
+// an ambiguity.
+type Confidence int
+
+const (
+	No    Confidence = iota // full confidence that there was no match
+	Low                     // most likely value picked out of a set of alternatives
+	High                    // value is generally assumed to be the correct match
+	Exact                   // exact match or explicitly specified value
+)
+
+var confName = []string{"No", "Low", "High", "Exact"}
+
+func (c Confidence) String() string {
+	return confName[c]
+}
+
+// String returns the canonical string representation of the language tag.
+func (t Tag) String() string {
+	return t.tag().String()
+}
+
+// MarshalText implements encoding.TextMarshaler.
+func (t Tag) MarshalText() (text []byte, err error) {
+	return t.tag().MarshalText()
+}
+
+// UnmarshalText implements encoding.TextUnmarshaler.
+func (t *Tag) UnmarshalText(text []byte) error {
+	var tag language.Tag
+	err := tag.UnmarshalText(text)
+	*t = makeTag(tag)
+	return err
+}
+
+// Base returns the base language of the language tag. If the base language is
+// unspecified, an attempt will be made to infer it from the context.
+// It uses a variant of CLDR's Add Likely Subtags algorithm. This is subject to change.
+func (t Tag) Base() (Base, Confidence) {
+	if b := t.lang(); b != 0 {
+		return Base{b}, Exact
+	}
+	tt := t.tag()
+	c := High
+	if tt.ScriptID == 0 && !tt.RegionID.IsCountry() {
+		c = Low
+	}
+	if tag, err := tt.Maximize(); err == nil && tag.LangID != 0 {
+		return Base{tag.LangID}, c
+	}
+	return Base{0}, No
+}
+
+// Script infers the script for the language tag. If it was not explicitly given, it will infer
+// a most likely candidate.
+// If more than one script is commonly used for a language, the most likely one
+// is returned with a low confidence indication. For example, it returns (Cyrl, Low)
+// for Serbian.
+// If a script cannot be inferred (Zzzz, No) is returned. We do not use Zyyy (undetermined)
+// as one would suspect from the IANA registry for BCP 47. In a Unicode context Zyyy marks
+// common characters (like 1, 2, 3, '.', etc.) and is therefore more like multiple scripts.
+// See https://www.unicode.org/reports/tr24/#Values for more details. Zzzz is also used for
+// unknown value in CLDR.  (Zzzz, Exact) is returned if Zzzz was explicitly specified.
+// Note that an inferred script is never guaranteed to be the correct one. Latin is
+// almost exclusively used for Afrikaans, but Arabic has been used for some texts
+// in the past.  Also, the script that is commonly used may change over time.
+// It uses a variant of CLDR's Add Likely Subtags algorithm. This is subject to change.
+func (t Tag) Script() (Script, Confidence) {
+	if scr := t.script(); scr != 0 {
+		return Script{scr}, Exact
+	}
+	tt := t.tag()
+	sc, c := language.Script(_Zzzz), No
+	if scr := tt.LangID.SuppressScript(); scr != 0 {
+		// Note: it is not always the case that a language with a suppress
+		// script value is only written in one script (e.g. kk, ms, pa).
+		if tt.RegionID == 0 {
+			return Script{scr}, High
+		}
+		sc, c = scr, High
+	}
+	if tag, err := tt.Maximize(); err == nil {
+		if tag.ScriptID != sc {
+			sc, c = tag.ScriptID, Low
+		}
+	} else {
+		tt, _ = canonicalize(Deprecated|Macro, tt)
+		if tag, err := tt.Maximize(); err == nil && tag.ScriptID != sc {
+			sc, c = tag.ScriptID, Low
+		}
+	}
+	return Script{sc}, c
+}
+
+// Region returns the region for the language tag. If it was not explicitly given, it will
+// infer a most likely candidate from the context.
+// It uses a variant of CLDR's Add Likely Subtags algorithm. This is subject to change.
+func (t Tag) Region() (Region, Confidence) {
+	if r := t.region(); r != 0 {
+		return Region{r}, Exact
+	}
+	tt := t.tag()
+	if tt, err := tt.Maximize(); err == nil {
+		return Region{tt.RegionID}, Low // TODO: differentiate between high and low.
+	}
+	tt, _ = canonicalize(Deprecated|Macro, tt)
+	if tag, err := tt.Maximize(); err == nil {
+		return Region{tag.RegionID}, Low
+	}
+	return Region{_ZZ}, No // TODO: return world instead of undetermined?
+}
+
+// Variants returns the variants specified explicitly for this language tag.
+// or nil if no variant was specified.
+func (t Tag) Variants() []Variant {
+	if !compact.Tag(t).MayHaveVariants() {
+		return nil
+	}
+	v := []Variant{}
+	x, str := "", t.tag().Variants()
+	for str != "" {
+		x, str = nextToken(str)
+		v = append(v, Variant{x})
+	}
+	return v
+}
+
+// Parent returns the CLDR parent of t. In CLDR, missing fields in data for a
+// specific language are substituted with fields from the parent language.
+// The parent for a language may change for newer versions of CLDR.
+//
+// Parent returns a tag for a less specific language that is mutually
+// intelligible or Und if there is no such language. This may not be the same as
+// simply stripping the last BCP 47 subtag. For instance, the parent of "zh-TW"
+// is "zh-Hant", and the parent of "zh-Hant" is "und".
+func (t Tag) Parent() Tag {
+	return Tag(compact.Tag(t).Parent())
+}
+
+// returns token t and the rest of the string.
+func nextToken(s string) (t, tail string) {
+	p := strings.Index(s[1:], "-")
+	if p == -1 {
+		return s[1:], ""
+	}
+	p++
+	return s[1:p], s[p:]
+}
+
+// Extension is a single BCP 47 extension.
+type Extension struct {
+	s string
+}
+
+// String returns the string representation of the extension, including the
+// type tag.
+func (e Extension) String() string {
+	return e.s
+}
+
+// ParseExtension parses s as an extension and returns it on success.
+func ParseExtension(s string) (e Extension, err error) {
+	ext, err := language.ParseExtension(s)
+	return Extension{ext}, err
+}
+
+// Type returns the one-byte extension type of e. It returns 0 for the zero
+// exception.
+func (e Extension) Type() byte {
+	if e.s == "" {
+		return 0
+	}
+	return e.s[0]
+}
+
+// Tokens returns the list of tokens of e.
+func (e Extension) Tokens() []string {
+	return strings.Split(e.s, "-")
+}
+
+// Extension returns the extension of type x for tag t. It will return
+// false for ok if t does not have the requested extension. The returned
+// extension will be invalid in this case.
+func (t Tag) Extension(x byte) (ext Extension, ok bool) {
+	if !compact.Tag(t).MayHaveExtensions() {
+		return Extension{}, false
+	}
+	e, ok := t.tag().Extension(x)
+	return Extension{e}, ok
+}
+
+// Extensions returns all extensions of t.
+func (t Tag) Extensions() []Extension {
+	if !compact.Tag(t).MayHaveExtensions() {
+		return nil
+	}
+	e := []Extension{}
+	for _, ext := range t.tag().Extensions() {
+		e = append(e, Extension{ext})
+	}
+	return e
+}
+
+// TypeForKey returns the type associated with the given key, where key and type
+// are of the allowed values defined for the Unicode locale extension ('u') in
+// https://www.unicode.org/reports/tr35/#Unicode_Language_and_Locale_Identifiers.
+// TypeForKey will traverse the inheritance chain to get the correct value.
+func (t Tag) TypeForKey(key string) string {
+	if !compact.Tag(t).MayHaveExtensions() {
+		if key != "rg" && key != "va" {
+			return ""
+		}
+	}
+	return t.tag().TypeForKey(key)
+}
+
+// SetTypeForKey returns a new Tag with the key set to type, where key and type
+// are of the allowed values defined for the Unicode locale extension ('u') in
+// https://www.unicode.org/reports/tr35/#Unicode_Language_and_Locale_Identifiers.
+// An empty value removes an existing pair with the same key.
+func (t Tag) SetTypeForKey(key, value string) (Tag, error) {
+	tt, err := t.tag().SetTypeForKey(key, value)
+	return makeTag(tt), err
+}
+
+// NumCompactTags is the number of compact tags. The maximum tag is
+// NumCompactTags-1.
+const NumCompactTags = compact.NumCompactTags
+
+// CompactIndex returns an index, where 0 <= index < NumCompactTags, for tags
+// for which data exists in the text repository.The index will change over time
+// and should not be stored in persistent storage. If t does not match a compact
+// index, exact will be false and the compact index will be returned for the
+// first match after repeatedly taking the Parent of t.
+func CompactIndex(t Tag) (index int, exact bool) {
+	id, exact := compact.LanguageID(compact.Tag(t))
+	return int(id), exact
+}
+
+var root = language.Tag{}
+
+// Base is an ISO 639 language code, used for encoding the base language
+// of a language tag.
+type Base struct {
+	langID language.Language
+}
+
+// ParseBase parses a 2- or 3-letter ISO 639 code.
+// It returns a ValueError if s is a well-formed but unknown language identifier
+// or another error if another error occurred.
+func ParseBase(s string) (Base, error) {
+	l, err := language.ParseBase(s)
+	return Base{l}, err
+}
+
+// String returns the BCP 47 representation of the base language.
+func (b Base) String() string {
+	return b.langID.String()
+}
+
+// ISO3 returns the ISO 639-3 language code.
+func (b Base) ISO3() string {
+	return b.langID.ISO3()
+}
+
+// IsPrivateUse reports whether this language code is reserved for private use.
+func (b Base) IsPrivateUse() bool {
+	return b.langID.IsPrivateUse()
+}
+
+// Script is a 4-letter ISO 15924 code for representing scripts.
+// It is idiomatically represented in title case.
+type Script struct {
+	scriptID language.Script
+}
+
+// ParseScript parses a 4-letter ISO 15924 code.
+// It returns a ValueError if s is a well-formed but unknown script identifier
+// or another error if another error occurred.
+func ParseScript(s string) (Script, error) {
+	sc, err := language.ParseScript(s)
+	return Script{sc}, err
+}
+
+// String returns the script code in title case.
+// It returns "Zzzz" for an unspecified script.
+func (s Script) String() string {
+	return s.scriptID.String()
+}
+
+// IsPrivateUse reports whether this script code is reserved for private use.
+func (s Script) IsPrivateUse() bool {
+	return s.scriptID.IsPrivateUse()
+}
+
+// Region is an ISO 3166-1 or UN M.49 code for representing countries and regions.
+type Region struct {
+	regionID language.Region
+}
+
+// EncodeM49 returns the Region for the given UN M.49 code.
+// It returns an error if r is not a valid code.
+func EncodeM49(r int) (Region, error) {
+	rid, err := language.EncodeM49(r)
+	return Region{rid}, err
+}
+
+// ParseRegion parses a 2- or 3-letter ISO 3166-1 or a UN M.49 code.
+// It returns a ValueError if s is a well-formed but unknown region identifier
+// or another error if another error occurred.
+func ParseRegion(s string) (Region, error) {
+	r, err := language.ParseRegion(s)
+	return Region{r}, err
+}
+
+// String returns the BCP 47 representation for the region.
+// It returns "ZZ" for an unspecified region.
+func (r Region) String() string {
+	return r.regionID.String()
+}
+
+// ISO3 returns the 3-letter ISO code of r.
+// Note that not all regions have a 3-letter ISO code.
+// In such cases this method returns "ZZZ".
+func (r Region) ISO3() string {
+	return r.regionID.ISO3()
+}
+
+// M49 returns the UN M.49 encoding of r, or 0 if this encoding
+// is not defined for r.
+func (r Region) M49() int {
+	return r.regionID.M49()
+}
+
+// IsPrivateUse reports whether r has the ISO 3166 User-assigned status. This
+// may include private-use tags that are assigned by CLDR and used in this
+// implementation. So IsPrivateUse and IsCountry can be simultaneously true.
+func (r Region) IsPrivateUse() bool {
+	return r.regionID.IsPrivateUse()
+}
+
+// IsCountry returns whether this region is a country or autonomous area. This
+// includes non-standard definitions from CLDR.
+func (r Region) IsCountry() bool {
+	return r.regionID.IsCountry()
+}
+
+// IsGroup returns whether this region defines a collection of regions. This
+// includes non-standard definitions from CLDR.
+func (r Region) IsGroup() bool {
+	return r.regionID.IsGroup()
+}
+
+// Contains returns whether Region c is contained by Region r. It returns true
+// if c == r.
+func (r Region) Contains(c Region) bool {
+	return r.regionID.Contains(c.regionID)
+}
+
+// TLD returns the country code top-level domain (ccTLD). UK is returned for GB.
+// In all other cases it returns either the region itself or an error.
+//
+// This method may return an error for a region for which there exists a
+// canonical form with a ccTLD. To get that ccTLD canonicalize r first. The
+// region will already be canonicalized it was obtained from a Tag that was
+// obtained using any of the default methods.
+func (r Region) TLD() (Region, error) {
+	tld, err := r.regionID.TLD()
+	return Region{tld}, err
+}
+
+// Canonicalize returns the region or a possible replacement if the region is
+// deprecated. It will not return a replacement for deprecated regions that
+// are split into multiple regions.
+func (r Region) Canonicalize() Region {
+	return Region{r.regionID.Canonicalize()}
+}
+
+// Variant represents a registered variant of a language as defined by BCP 47.
+type Variant struct {
+	variant string
+}
+
+// ParseVariant parses and returns a Variant. An error is returned if s is not
+// a valid variant.
+func ParseVariant(s string) (Variant, error) {
+	v, err := language.ParseVariant(s)
+	return Variant{v.String()}, err
+}
+
+// String returns the string representation of the variant.
+func (v Variant) String() string {
+	return v.variant
+}
diff --git a/vendor/golang.org/x/text/language/match.go b/vendor/golang.org/x/text/language/match.go
new file mode 100644
index 0000000..f734921
--- /dev/null
+++ b/vendor/golang.org/x/text/language/match.go
@@ -0,0 +1,735 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package language
+
+import (
+	"errors"
+	"strings"
+
+	"golang.org/x/text/internal/language"
+)
+
+// A MatchOption configures a Matcher.
+type MatchOption func(*matcher)
+
+// PreferSameScript will, in the absence of a match, result in the first
+// preferred tag with the same script as a supported tag to match this supported
+// tag. The default is currently true, but this may change in the future.
+func PreferSameScript(preferSame bool) MatchOption {
+	return func(m *matcher) { m.preferSameScript = preferSame }
+}
+
+// TODO(v1.0.0): consider making Matcher a concrete type, instead of interface.
+// There doesn't seem to be too much need for multiple types.
+// Making it a concrete type allows MatchStrings to be a method, which will
+// improve its discoverability.
+
+// MatchStrings parses and matches the given strings until one of them matches
+// the language in the Matcher. A string may be an Accept-Language header as
+// handled by ParseAcceptLanguage. The default language is returned if no
+// other language matched.
+func MatchStrings(m Matcher, lang ...string) (tag Tag, index int) {
+	for _, accept := range lang {
+		desired, _, err := ParseAcceptLanguage(accept)
+		if err != nil {
+			continue
+		}
+		if tag, index, conf := m.Match(desired...); conf != No {
+			return tag, index
+		}
+	}
+	tag, index, _ = m.Match()
+	return
+}
+
+// Matcher is the interface that wraps the Match method.
+//
+// Match returns the best match for any of the given tags, along with
+// a unique index associated with the returned tag and a confidence
+// score.
+type Matcher interface {
+	Match(t ...Tag) (tag Tag, index int, c Confidence)
+}
+
+// Comprehends reports the confidence score for a speaker of a given language
+// to being able to comprehend the written form of an alternative language.
+func Comprehends(speaker, alternative Tag) Confidence {
+	_, _, c := NewMatcher([]Tag{alternative}).Match(speaker)
+	return c
+}
+
+// NewMatcher returns a Matcher that matches an ordered list of preferred tags
+// against a list of supported tags based on written intelligibility, closeness
+// of dialect, equivalence of subtags and various other rules. It is initialized
+// with the list of supported tags. The first element is used as the default
+// value in case no match is found.
+//
+// Its Match method matches the first of the given Tags to reach a certain
+// confidence threshold. The tags passed to Match should therefore be specified
+// in order of preference. Extensions are ignored for matching.
+//
+// The index returned by the Match method corresponds to the index of the
+// matched tag in t, but is augmented with the Unicode extension ('u')of the
+// corresponding preferred tag. This allows user locale options to be passed
+// transparently.
+func NewMatcher(t []Tag, options ...MatchOption) Matcher {
+	return newMatcher(t, options)
+}
+
+func (m *matcher) Match(want ...Tag) (t Tag, index int, c Confidence) {
+	var tt language.Tag
+	match, w, c := m.getBest(want...)
+	if match != nil {
+		tt, index = match.tag, match.index
+	} else {
+		// TODO: this should be an option
+		tt = m.default_.tag
+		if m.preferSameScript {
+		outer:
+			for _, w := range want {
+				script, _ := w.Script()
+				if script.scriptID == 0 {
+					// Don't do anything if there is no script, such as with
+					// private subtags.
+					continue
+				}
+				for i, h := range m.supported {
+					if script.scriptID == h.maxScript {
+						tt, index = h.tag, i
+						break outer
+					}
+				}
+			}
+		}
+		// TODO: select first language tag based on script.
+	}
+	if w.RegionID != tt.RegionID && w.RegionID != 0 {
+		if w.RegionID != 0 && tt.RegionID != 0 && tt.RegionID.Contains(w.RegionID) {
+			tt.RegionID = w.RegionID
+			tt.RemakeString()
+		} else if r := w.RegionID.String(); len(r) == 2 {
+			// TODO: also filter macro and deprecated.
+			tt, _ = tt.SetTypeForKey("rg", strings.ToLower(r)+"zzzz")
+		}
+	}
+	// Copy options from the user-provided tag into the result tag. This is hard
+	// to do after the fact, so we do it here.
+	// TODO: add in alternative variants to -u-va-.
+	// TODO: add preferred region to -u-rg-.
+	if e := w.Extensions(); len(e) > 0 {
+		b := language.Builder{}
+		b.SetTag(tt)
+		for _, e := range e {
+			b.AddExt(e)
+		}
+		tt = b.Make()
+	}
+	return makeTag(tt), index, c
+}
+
+// ErrMissingLikelyTagsData indicates no information was available
+// to compute likely values of missing tags.
+var ErrMissingLikelyTagsData = errors.New("missing likely tags data")
+
+// func (t *Tag) setTagsFrom(id Tag) {
+// 	t.LangID = id.LangID
+// 	t.ScriptID = id.ScriptID
+// 	t.RegionID = id.RegionID
+// }
+
+// Tag Matching
+// CLDR defines an algorithm for finding the best match between two sets of language
+// tags. The basic algorithm defines how to score a possible match and then find
+// the match with the best score
+// (see https://www.unicode.org/reports/tr35/#LanguageMatching).
+// Using scoring has several disadvantages. The scoring obfuscates the importance of
+// the various factors considered, making the algorithm harder to understand. Using
+// scoring also requires the full score to be computed for each pair of tags.
+//
+// We will use a different algorithm which aims to have the following properties:
+// - clarity on the precedence of the various selection factors, and
+// - improved performance by allowing early termination of a comparison.
+//
+// Matching algorithm (overview)
+// Input:
+//   - supported: a set of supported tags
+//   - default:   the default tag to return in case there is no match
+//   - desired:   list of desired tags, ordered by preference, starting with
+//                the most-preferred.
+//
+// Algorithm:
+//   1) Set the best match to the lowest confidence level
+//   2) For each tag in "desired":
+//     a) For each tag in "supported":
+//        1) compute the match between the two tags.
+//        2) if the match is better than the previous best match, replace it
+//           with the new match. (see next section)
+//     b) if the current best match is Exact and pin is true the result will be
+//        frozen to the language found thusfar, although better matches may
+//        still be found for the same language.
+//   3) If the best match so far is below a certain threshold, return "default".
+//
+// Ranking:
+// We use two phases to determine whether one pair of tags are a better match
+// than another pair of tags. First, we determine a rough confidence level. If the
+// levels are different, the one with the highest confidence wins.
+// Second, if the rough confidence levels are identical, we use a set of tie-breaker
+// rules.
+//
+// The confidence level of matching a pair of tags is determined by finding the
+// lowest confidence level of any matches of the corresponding subtags (the
+// result is deemed as good as its weakest link).
+// We define the following levels:
+//   Exact    - An exact match of a subtag, before adding likely subtags.
+//   MaxExact - An exact match of a subtag, after adding likely subtags.
+//              [See Note 2].
+//   High     - High level of mutual intelligibility between different subtag
+//              variants.
+//   Low      - Low level of mutual intelligibility between different subtag
+//              variants.
+//   No       - No mutual intelligibility.
+//
+// The following levels can occur for each type of subtag:
+//   Base:    Exact, MaxExact, High, Low, No
+//   Script:  Exact, MaxExact [see Note 3], Low, No
+//   Region:  Exact, MaxExact, High
+//   Variant: Exact, High
+//   Private: Exact, No
+//
+// Any result with a confidence level of Low or higher is deemed a possible match.
+// Once a desired tag matches any of the supported tags with a level of MaxExact
+// or higher, the next desired tag is not considered (see Step 2.b).
+// Note that CLDR provides languageMatching data that defines close equivalence
+// classes for base languages, scripts and regions.
+//
+// Tie-breaking
+// If we get the same confidence level for two matches, we apply a sequence of
+// tie-breaking rules. The first that succeeds defines the result. The rules are
+// applied in the following order.
+//   1) Original language was defined and was identical.
+//   2) Original region was defined and was identical.
+//   3) Distance between two maximized regions was the smallest.
+//   4) Original script was defined and was identical.
+//   5) Distance from want tag to have tag using the parent relation [see Note 5.]
+// If there is still no winner after these rules are applied, the first match
+// found wins.
+//
+// Notes:
+// [2] In practice, as matching of Exact is done in a separate phase from
+//     matching the other levels, we reuse the Exact level to mean MaxExact in
+//     the second phase. As a consequence, we only need the levels defined by
+//     the Confidence type. The MaxExact confidence level is mapped to High in
+//     the public API.
+// [3] We do not differentiate between maximized script values that were derived
+//     from suppressScript versus most likely tag data. We determined that in
+//     ranking the two, one ranks just after the other. Moreover, the two cannot
+//     occur concurrently. As a consequence, they are identical for practical
+//     purposes.
+// [4] In case of deprecated, macro-equivalents and legacy mappings, we assign
+//     the MaxExact level to allow iw vs he to still be a closer match than
+//     en-AU vs en-US, for example.
+// [5] In CLDR a locale inherits fields that are unspecified for this locale
+//     from its parent. Therefore, if a locale is a parent of another locale,
+//     it is a strong measure for closeness, especially when no other tie
+//     breaker rule applies. One could also argue it is inconsistent, for
+//     example, when pt-AO matches pt (which CLDR equates with pt-BR), even
+//     though its parent is pt-PT according to the inheritance rules.
+//
+// Implementation Details:
+// There are several performance considerations worth pointing out. Most notably,
+// we preprocess as much as possible (within reason) at the time of creation of a
+// matcher. This includes:
+//   - creating a per-language map, which includes data for the raw base language
+//     and its canonicalized variant (if applicable),
+//   - expanding entries for the equivalence classes defined in CLDR's
+//     languageMatch data.
+// The per-language map ensures that typically only a very small number of tags
+// need to be considered. The pre-expansion of canonicalized subtags and
+// equivalence classes reduces the amount of map lookups that need to be done at
+// runtime.
+
+// matcher keeps a set of supported language tags, indexed by language.
+type matcher struct {
+	default_         *haveTag
+	supported        []*haveTag
+	index            map[language.Language]*matchHeader
+	passSettings     bool
+	preferSameScript bool
+}
+
+// matchHeader has the lists of tags for exact matches and matches based on
+// maximized and canonicalized tags for a given language.
+type matchHeader struct {
+	haveTags []*haveTag
+	original bool
+}
+
+// haveTag holds a supported Tag and its maximized script and region. The maximized
+// or canonicalized language is not stored as it is not needed during matching.
+type haveTag struct {
+	tag language.Tag
+
+	// index of this tag in the original list of supported tags.
+	index int
+
+	// conf is the maximum confidence that can result from matching this haveTag.
+	// When conf < Exact this means it was inserted after applying a CLDR equivalence rule.
+	conf Confidence
+
+	// Maximized region and script.
+	maxRegion language.Region
+	maxScript language.Script
+
+	// altScript may be checked as an alternative match to maxScript. If altScript
+	// matches, the confidence level for this match is Low. Theoretically there
+	// could be multiple alternative scripts. This does not occur in practice.
+	altScript language.Script
+
+	// nextMax is the index of the next haveTag with the same maximized tags.
+	nextMax uint16
+}
+
+func makeHaveTag(tag language.Tag, index int) (haveTag, language.Language) {
+	max := tag
+	if tag.LangID != 0 || tag.RegionID != 0 || tag.ScriptID != 0 {
+		max, _ = canonicalize(All, max)
+		max, _ = max.Maximize()
+		max.RemakeString()
+	}
+	return haveTag{tag, index, Exact, max.RegionID, max.ScriptID, altScript(max.LangID, max.ScriptID), 0}, max.LangID
+}
+
+// altScript returns an alternative script that may match the given script with
+// a low confidence.  At the moment, the langMatch data allows for at most one
+// script to map to another and we rely on this to keep the code simple.
+func altScript(l language.Language, s language.Script) language.Script {
+	for _, alt := range matchScript {
+		// TODO: also match cases where language is not the same.
+		if (language.Language(alt.wantLang) == l || language.Language(alt.haveLang) == l) &&
+			language.Script(alt.haveScript) == s {
+			return language.Script(alt.wantScript)
+		}
+	}
+	return 0
+}
+
+// addIfNew adds a haveTag to the list of tags only if it is a unique tag.
+// Tags that have the same maximized values are linked by index.
+func (h *matchHeader) addIfNew(n haveTag, exact bool) {
+	h.original = h.original || exact
+	// Don't add new exact matches.
+	for _, v := range h.haveTags {
+		if equalsRest(v.tag, n.tag) {
+			return
+		}
+	}
+	// Allow duplicate maximized tags, but create a linked list to allow quickly
+	// comparing the equivalents and bail out.
+	for i, v := range h.haveTags {
+		if v.maxScript == n.maxScript &&
+			v.maxRegion == n.maxRegion &&
+			v.tag.VariantOrPrivateUseTags() == n.tag.VariantOrPrivateUseTags() {
+			for h.haveTags[i].nextMax != 0 {
+				i = int(h.haveTags[i].nextMax)
+			}
+			h.haveTags[i].nextMax = uint16(len(h.haveTags))
+			break
+		}
+	}
+	h.haveTags = append(h.haveTags, &n)
+}
+
+// header returns the matchHeader for the given language. It creates one if
+// it doesn't already exist.
+func (m *matcher) header(l language.Language) *matchHeader {
+	if h := m.index[l]; h != nil {
+		return h
+	}
+	h := &matchHeader{}
+	m.index[l] = h
+	return h
+}
+
+func toConf(d uint8) Confidence {
+	if d <= 10 {
+		return High
+	}
+	if d < 30 {
+		return Low
+	}
+	return No
+}
+
+// newMatcher builds an index for the given supported tags and returns it as
+// a matcher. It also expands the index by considering various equivalence classes
+// for a given tag.
+func newMatcher(supported []Tag, options []MatchOption) *matcher {
+	m := &matcher{
+		index:            make(map[language.Language]*matchHeader),
+		preferSameScript: true,
+	}
+	for _, o := range options {
+		o(m)
+	}
+	if len(supported) == 0 {
+		m.default_ = &haveTag{}
+		return m
+	}
+	// Add supported languages to the index. Add exact matches first to give
+	// them precedence.
+	for i, tag := range supported {
+		tt := tag.tag()
+		pair, _ := makeHaveTag(tt, i)
+		m.header(tt.LangID).addIfNew(pair, true)
+		m.supported = append(m.supported, &pair)
+	}
+	m.default_ = m.header(supported[0].lang()).haveTags[0]
+	// Keep these in two different loops to support the case that two equivalent
+	// languages are distinguished, such as iw and he.
+	for i, tag := range supported {
+		tt := tag.tag()
+		pair, max := makeHaveTag(tt, i)
+		if max != tt.LangID {
+			m.header(max).addIfNew(pair, true)
+		}
+	}
+
+	// update is used to add indexes in the map for equivalent languages.
+	// update will only add entries to original indexes, thus not computing any
+	// transitive relations.
+	update := func(want, have uint16, conf Confidence) {
+		if hh := m.index[language.Language(have)]; hh != nil {
+			if !hh.original {
+				return
+			}
+			hw := m.header(language.Language(want))
+			for _, ht := range hh.haveTags {
+				v := *ht
+				if conf < v.conf {
+					v.conf = conf
+				}
+				v.nextMax = 0 // this value needs to be recomputed
+				if v.altScript != 0 {
+					v.altScript = altScript(language.Language(want), v.maxScript)
+				}
+				hw.addIfNew(v, conf == Exact && hh.original)
+			}
+		}
+	}
+
+	// Add entries for languages with mutual intelligibility as defined by CLDR's
+	// languageMatch data.
+	for _, ml := range matchLang {
+		update(ml.want, ml.have, toConf(ml.distance))
+		if !ml.oneway {
+			update(ml.have, ml.want, toConf(ml.distance))
+		}
+	}
+
+	// Add entries for possible canonicalizations. This is an optimization to
+	// ensure that only one map lookup needs to be done at runtime per desired tag.
+	// First we match deprecated equivalents. If they are perfect equivalents
+	// (their canonicalization simply substitutes a different language code, but
+	// nothing else), the match confidence is Exact, otherwise it is High.
+	for i, lm := range language.AliasMap {
+		// If deprecated codes match and there is no fiddling with the script or
+		// or region, we consider it an exact match.
+		conf := Exact
+		if language.AliasTypes[i] != language.Macro {
+			if !isExactEquivalent(language.Language(lm.From)) {
+				conf = High
+			}
+			update(lm.To, lm.From, conf)
+		}
+		update(lm.From, lm.To, conf)
+	}
+	return m
+}
+
+// getBest gets the best matching tag in m for any of the given tags, taking into
+// account the order of preference of the given tags.
+func (m *matcher) getBest(want ...Tag) (got *haveTag, orig language.Tag, c Confidence) {
+	best := bestMatch{}
+	for i, ww := range want {
+		w := ww.tag()
+		var max language.Tag
+		// Check for exact match first.
+		h := m.index[w.LangID]
+		if w.LangID != 0 {
+			if h == nil {
+				continue
+			}
+			// Base language is defined.
+			max, _ = canonicalize(Legacy|Deprecated|Macro, w)
+			// A region that is added through canonicalization is stronger than
+			// a maximized region: set it in the original (e.g. mo -> ro-MD).
+			if w.RegionID != max.RegionID {
+				w.RegionID = max.RegionID
+			}
+			// TODO: should we do the same for scripts?
+			// See test case: en, sr, nl ; sh ; sr
+			max, _ = max.Maximize()
+		} else {
+			// Base language is not defined.
+			if h != nil {
+				for i := range h.haveTags {
+					have := h.haveTags[i]
+					if equalsRest(have.tag, w) {
+						return have, w, Exact
+					}
+				}
+			}
+			if w.ScriptID == 0 && w.RegionID == 0 {
+				// We skip all tags matching und for approximate matching, including
+				// private tags.
+				continue
+			}
+			max, _ = w.Maximize()
+			if h = m.index[max.LangID]; h == nil {
+				continue
+			}
+		}
+		pin := true
+		for _, t := range want[i+1:] {
+			if w.LangID == t.lang() {
+				pin = false
+				break
+			}
+		}
+		// Check for match based on maximized tag.
+		for i := range h.haveTags {
+			have := h.haveTags[i]
+			best.update(have, w, max.ScriptID, max.RegionID, pin)
+			if best.conf == Exact {
+				for have.nextMax != 0 {
+					have = h.haveTags[have.nextMax]
+					best.update(have, w, max.ScriptID, max.RegionID, pin)
+				}
+				return best.have, best.want, best.conf
+			}
+		}
+	}
+	if best.conf <= No {
+		if len(want) != 0 {
+			return nil, want[0].tag(), No
+		}
+		return nil, language.Tag{}, No
+	}
+	return best.have, best.want, best.conf
+}
+
+// bestMatch accumulates the best match so far.
+type bestMatch struct {
+	have            *haveTag
+	want            language.Tag
+	conf            Confidence
+	pinnedRegion    language.Region
+	pinLanguage     bool
+	sameRegionGroup bool
+	// Cached results from applying tie-breaking rules.
+	origLang     bool
+	origReg      bool
+	paradigmReg  bool
+	regGroupDist uint8
+	origScript   bool
+}
+
+// update updates the existing best match if the new pair is considered to be a
+// better match. To determine if the given pair is a better match, it first
+// computes the rough confidence level. If this surpasses the current match, it
+// will replace it and update the tie-breaker rule cache. If there is a tie, it
+// proceeds with applying a series of tie-breaker rules. If there is no
+// conclusive winner after applying the tie-breaker rules, it leaves the current
+// match as the preferred match.
+//
+// If pin is true and have and tag are a strong match, it will henceforth only
+// consider matches for this language. This corresponds to the nothing that most
+// users have a strong preference for the first defined language. A user can
+// still prefer a second language over a dialect of the preferred language by
+// explicitly specifying dialects, e.g. "en, nl, en-GB". In this case pin should
+// be false.
+func (m *bestMatch) update(have *haveTag, tag language.Tag, maxScript language.Script, maxRegion language.Region, pin bool) {
+	// Bail if the maximum attainable confidence is below that of the current best match.
+	c := have.conf
+	if c < m.conf {
+		return
+	}
+	// Don't change the language once we already have found an exact match.
+	if m.pinLanguage && tag.LangID != m.want.LangID {
+		return
+	}
+	// Pin the region group if we are comparing tags for the same language.
+	if tag.LangID == m.want.LangID && m.sameRegionGroup {
+		_, sameGroup := regionGroupDist(m.pinnedRegion, have.maxRegion, have.maxScript, m.want.LangID)
+		if !sameGroup {
+			return
+		}
+	}
+	if c == Exact && have.maxScript == maxScript {
+		// If there is another language and then another entry of this language,
+		// don't pin anything, otherwise pin the language.
+		m.pinLanguage = pin
+	}
+	if equalsRest(have.tag, tag) {
+	} else if have.maxScript != maxScript {
+		// There is usually very little comprehension between different scripts.
+		// In a few cases there may still be Low comprehension. This possibility
+		// is pre-computed and stored in have.altScript.
+		if Low < m.conf || have.altScript != maxScript {
+			return
+		}
+		c = Low
+	} else if have.maxRegion != maxRegion {
+		if High < c {
+			// There is usually a small difference between languages across regions.
+			c = High
+		}
+	}
+
+	// We store the results of the computations of the tie-breaker rules along
+	// with the best match. There is no need to do the checks once we determine
+	// we have a winner, but we do still need to do the tie-breaker computations.
+	// We use "beaten" to keep track if we still need to do the checks.
+	beaten := false // true if the new pair defeats the current one.
+	if c != m.conf {
+		if c < m.conf {
+			return
+		}
+		beaten = true
+	}
+
+	// Tie-breaker rules:
+	// We prefer if the pre-maximized language was specified and identical.
+	origLang := have.tag.LangID == tag.LangID && tag.LangID != 0
+	if !beaten && m.origLang != origLang {
+		if m.origLang {
+			return
+		}
+		beaten = true
+	}
+
+	// We prefer if the pre-maximized region was specified and identical.
+	origReg := have.tag.RegionID == tag.RegionID && tag.RegionID != 0
+	if !beaten && m.origReg != origReg {
+		if m.origReg {
+			return
+		}
+		beaten = true
+	}
+
+	regGroupDist, sameGroup := regionGroupDist(have.maxRegion, maxRegion, maxScript, tag.LangID)
+	if !beaten && m.regGroupDist != regGroupDist {
+		if regGroupDist > m.regGroupDist {
+			return
+		}
+		beaten = true
+	}
+
+	paradigmReg := isParadigmLocale(tag.LangID, have.maxRegion)
+	if !beaten && m.paradigmReg != paradigmReg {
+		if !paradigmReg {
+			return
+		}
+		beaten = true
+	}
+
+	// Next we prefer if the pre-maximized script was specified and identical.
+	origScript := have.tag.ScriptID == tag.ScriptID && tag.ScriptID != 0
+	if !beaten && m.origScript != origScript {
+		if m.origScript {
+			return
+		}
+		beaten = true
+	}
+
+	// Update m to the newly found best match.
+	if beaten {
+		m.have = have
+		m.want = tag
+		m.conf = c
+		m.pinnedRegion = maxRegion
+		m.sameRegionGroup = sameGroup
+		m.origLang = origLang
+		m.origReg = origReg
+		m.paradigmReg = paradigmReg
+		m.origScript = origScript
+		m.regGroupDist = regGroupDist
+	}
+}
+
+func isParadigmLocale(lang language.Language, r language.Region) bool {
+	for _, e := range paradigmLocales {
+		if language.Language(e[0]) == lang && (r == language.Region(e[1]) || r == language.Region(e[2])) {
+			return true
+		}
+	}
+	return false
+}
+
+// regionGroupDist computes the distance between two regions based on their
+// CLDR grouping.
+func regionGroupDist(a, b language.Region, script language.Script, lang language.Language) (dist uint8, same bool) {
+	const defaultDistance = 4
+
+	aGroup := uint(regionToGroups[a]) << 1
+	bGroup := uint(regionToGroups[b]) << 1
+	for _, ri := range matchRegion {
+		if language.Language(ri.lang) == lang && (ri.script == 0 || language.Script(ri.script) == script) {
+			group := uint(1 << (ri.group &^ 0x80))
+			if 0x80&ri.group == 0 {
+				if aGroup&bGroup&group != 0 { // Both regions are in the group.
+					return ri.distance, ri.distance == defaultDistance
+				}
+			} else {
+				if (aGroup|bGroup)&group == 0 { // Both regions are not in the group.
+					return ri.distance, ri.distance == defaultDistance
+				}
+			}
+		}
+	}
+	return defaultDistance, true
+}
+
+// equalsRest compares everything except the language.
+func equalsRest(a, b language.Tag) bool {
+	// TODO: don't include extensions in this comparison. To do this efficiently,
+	// though, we should handle private tags separately.
+	return a.ScriptID == b.ScriptID && a.RegionID == b.RegionID && a.VariantOrPrivateUseTags() == b.VariantOrPrivateUseTags()
+}
+
+// isExactEquivalent returns true if canonicalizing the language will not alter
+// the script or region of a tag.
+func isExactEquivalent(l language.Language) bool {
+	for _, o := range notEquivalent {
+		if o == l {
+			return false
+		}
+	}
+	return true
+}
+
+var notEquivalent []language.Language
+
+func init() {
+	// Create a list of all languages for which canonicalization may alter the
+	// script or region.
+	for _, lm := range language.AliasMap {
+		tag := language.Tag{LangID: language.Language(lm.From)}
+		if tag, _ = canonicalize(All, tag); tag.ScriptID != 0 || tag.RegionID != 0 {
+			notEquivalent = append(notEquivalent, language.Language(lm.From))
+		}
+	}
+	// Maximize undefined regions of paradigm locales.
+	for i, v := range paradigmLocales {
+		t := language.Tag{LangID: language.Language(v[0])}
+		max, _ := t.Maximize()
+		if v[1] == 0 {
+			paradigmLocales[i][1] = uint16(max.RegionID)
+		}
+		if v[2] == 0 {
+			paradigmLocales[i][2] = uint16(max.RegionID)
+		}
+	}
+}
diff --git a/vendor/golang.org/x/text/language/parse.go b/vendor/golang.org/x/text/language/parse.go
new file mode 100644
index 0000000..11acfd8
--- /dev/null
+++ b/vendor/golang.org/x/text/language/parse.go
@@ -0,0 +1,228 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package language
+
+import (
+	"errors"
+	"strconv"
+	"strings"
+
+	"golang.org/x/text/internal/language"
+)
+
+// ValueError is returned by any of the parsing functions when the
+// input is well-formed but the respective subtag is not recognized
+// as a valid value.
+type ValueError interface {
+	error
+
+	// Subtag returns the subtag for which the error occurred.
+	Subtag() string
+}
+
+// Parse parses the given BCP 47 string and returns a valid Tag. If parsing
+// failed it returns an error and any part of the tag that could be parsed.
+// If parsing succeeded but an unknown value was found, it returns
+// ValueError. The Tag returned in this case is just stripped of the unknown
+// value. All other values are preserved. It accepts tags in the BCP 47 format
+// and extensions to this standard defined in
+// https://www.unicode.org/reports/tr35/#Unicode_Language_and_Locale_Identifiers.
+// The resulting tag is canonicalized using the default canonicalization type.
+func Parse(s string) (t Tag, err error) {
+	return Default.Parse(s)
+}
+
+// Parse parses the given BCP 47 string and returns a valid Tag. If parsing
+// failed it returns an error and any part of the tag that could be parsed.
+// If parsing succeeded but an unknown value was found, it returns
+// ValueError. The Tag returned in this case is just stripped of the unknown
+// value. All other values are preserved. It accepts tags in the BCP 47 format
+// and extensions to this standard defined in
+// https://www.unicode.org/reports/tr35/#Unicode_Language_and_Locale_Identifiers.
+// The resulting tag is canonicalized using the canonicalization type c.
+func (c CanonType) Parse(s string) (t Tag, err error) {
+	tt, err := language.Parse(s)
+	if err != nil {
+		return makeTag(tt), err
+	}
+	tt, changed := canonicalize(c, tt)
+	if changed {
+		tt.RemakeString()
+	}
+	return makeTag(tt), err
+}
+
+// Compose creates a Tag from individual parts, which may be of type Tag, Base,
+// Script, Region, Variant, []Variant, Extension, []Extension or error. If a
+// Base, Script or Region or slice of type Variant or Extension is passed more
+// than once, the latter will overwrite the former. Variants and Extensions are
+// accumulated, but if two extensions of the same type are passed, the latter
+// will replace the former. For -u extensions, though, the key-type pairs are
+// added, where later values overwrite older ones. A Tag overwrites all former
+// values and typically only makes sense as the first argument. The resulting
+// tag is returned after canonicalizing using the Default CanonType. If one or
+// more errors are encountered, one of the errors is returned.
+func Compose(part ...interface{}) (t Tag, err error) {
+	return Default.Compose(part...)
+}
+
+// Compose creates a Tag from individual parts, which may be of type Tag, Base,
+// Script, Region, Variant, []Variant, Extension, []Extension or error. If a
+// Base, Script or Region or slice of type Variant or Extension is passed more
+// than once, the latter will overwrite the former. Variants and Extensions are
+// accumulated, but if two extensions of the same type are passed, the latter
+// will replace the former. For -u extensions, though, the key-type pairs are
+// added, where later values overwrite older ones. A Tag overwrites all former
+// values and typically only makes sense as the first argument. The resulting
+// tag is returned after canonicalizing using CanonType c. If one or more errors
+// are encountered, one of the errors is returned.
+func (c CanonType) Compose(part ...interface{}) (t Tag, err error) {
+	var b language.Builder
+	if err = update(&b, part...); err != nil {
+		return und, err
+	}
+	b.Tag, _ = canonicalize(c, b.Tag)
+	return makeTag(b.Make()), err
+}
+
+var errInvalidArgument = errors.New("invalid Extension or Variant")
+
+func update(b *language.Builder, part ...interface{}) (err error) {
+	for _, x := range part {
+		switch v := x.(type) {
+		case Tag:
+			b.SetTag(v.tag())
+		case Base:
+			b.Tag.LangID = v.langID
+		case Script:
+			b.Tag.ScriptID = v.scriptID
+		case Region:
+			b.Tag.RegionID = v.regionID
+		case Variant:
+			if v.variant == "" {
+				err = errInvalidArgument
+				break
+			}
+			b.AddVariant(v.variant)
+		case Extension:
+			if v.s == "" {
+				err = errInvalidArgument
+				break
+			}
+			b.SetExt(v.s)
+		case []Variant:
+			b.ClearVariants()
+			for _, v := range v {
+				b.AddVariant(v.variant)
+			}
+		case []Extension:
+			b.ClearExtensions()
+			for _, e := range v {
+				b.SetExt(e.s)
+			}
+		// TODO: support parsing of raw strings based on morphology or just extensions?
+		case error:
+			if v != nil {
+				err = v
+			}
+		}
+	}
+	return
+}
+
+var errInvalidWeight = errors.New("ParseAcceptLanguage: invalid weight")
+
+// ParseAcceptLanguage parses the contents of an Accept-Language header as
+// defined in http://www.ietf.org/rfc/rfc2616.txt and returns a list of Tags and
+// a list of corresponding quality weights. It is more permissive than RFC 2616
+// and may return non-nil slices even if the input is not valid.
+// The Tags will be sorted by highest weight first and then by first occurrence.
+// Tags with a weight of zero will be dropped. An error will be returned if the
+// input could not be parsed.
+func ParseAcceptLanguage(s string) (tag []Tag, q []float32, err error) {
+	var entry string
+	for s != "" {
+		if entry, s = split(s, ','); entry == "" {
+			continue
+		}
+
+		entry, weight := split(entry, ';')
+
+		// Scan the language.
+		t, err := Parse(entry)
+		if err != nil {
+			id, ok := acceptFallback[entry]
+			if !ok {
+				return nil, nil, err
+			}
+			t = makeTag(language.Tag{LangID: id})
+		}
+
+		// Scan the optional weight.
+		w := 1.0
+		if weight != "" {
+			weight = consume(weight, 'q')
+			weight = consume(weight, '=')
+			// consume returns the empty string when a token could not be
+			// consumed, resulting in an error for ParseFloat.
+			if w, err = strconv.ParseFloat(weight, 32); err != nil {
+				return nil, nil, errInvalidWeight
+			}
+			// Drop tags with a quality weight of 0.
+			if w <= 0 {
+				continue
+			}
+		}
+
+		tag = append(tag, t)
+		q = append(q, float32(w))
+	}
+	sortStable(&tagSort{tag, q})
+	return tag, q, nil
+}
+
+// consume removes a leading token c from s and returns the result or the empty
+// string if there is no such token.
+func consume(s string, c byte) string {
+	if s == "" || s[0] != c {
+		return ""
+	}
+	return strings.TrimSpace(s[1:])
+}
+
+func split(s string, c byte) (head, tail string) {
+	if i := strings.IndexByte(s, c); i >= 0 {
+		return strings.TrimSpace(s[:i]), strings.TrimSpace(s[i+1:])
+	}
+	return strings.TrimSpace(s), ""
+}
+
+// Add hack mapping to deal with a small number of cases that occur
+// in Accept-Language (with reasonable frequency).
+var acceptFallback = map[string]language.Language{
+	"english": _en,
+	"deutsch": _de,
+	"italian": _it,
+	"french":  _fr,
+	"*":       _mul, // defined in the spec to match all languages.
+}
+
+type tagSort struct {
+	tag []Tag
+	q   []float32
+}
+
+func (s *tagSort) Len() int {
+	return len(s.q)
+}
+
+func (s *tagSort) Less(i, j int) bool {
+	return s.q[i] > s.q[j]
+}
+
+func (s *tagSort) Swap(i, j int) {
+	s.tag[i], s.tag[j] = s.tag[j], s.tag[i]
+	s.q[i], s.q[j] = s.q[j], s.q[i]
+}
diff --git a/vendor/golang.org/x/text/language/tables.go b/vendor/golang.org/x/text/language/tables.go
new file mode 100644
index 0000000..e228077
--- /dev/null
+++ b/vendor/golang.org/x/text/language/tables.go
@@ -0,0 +1,298 @@
+// Code generated by running "go generate" in golang.org/x/text. DO NOT EDIT.
+
+package language
+
+// CLDRVersion is the CLDR version from which the tables in this package are derived.
+const CLDRVersion = "32"
+
+const (
+	_de  = 269
+	_en  = 313
+	_fr  = 350
+	_it  = 505
+	_mo  = 784
+	_no  = 879
+	_nb  = 839
+	_pt  = 960
+	_sh  = 1031
+	_mul = 806
+	_und = 0
+)
+const (
+	_001 = 1
+	_419 = 31
+	_BR  = 65
+	_CA  = 73
+	_ES  = 110
+	_GB  = 123
+	_MD  = 188
+	_PT  = 238
+	_UK  = 306
+	_US  = 309
+	_ZZ  = 357
+	_XA  = 323
+	_XC  = 325
+	_XK  = 333
+)
+const (
+	_Latn = 87
+	_Hani = 54
+	_Hans = 56
+	_Hant = 57
+	_Qaaa = 139
+	_Qaai = 147
+	_Qabx = 188
+	_Zinh = 236
+	_Zyyy = 241
+	_Zzzz = 242
+)
+
+var regionToGroups = []uint8{ // 357 elements
+	// Entry 0 - 3F
+	0x00, 0x00, 0x00, 0x04, 0x04, 0x00, 0x00, 0x04,
+	0x00, 0x00, 0x00, 0x00, 0x04, 0x04, 0x04, 0x00,
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04,
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x04, 0x00,
+	0x00, 0x04, 0x00, 0x00, 0x04, 0x01, 0x00, 0x00,
+	0x04, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00, 0x04, 0x04, 0x00, 0x04,
+	// Entry 40 - 7F
+	0x04, 0x04, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0x04, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0x00, 0x04, 0x00, 0x00, 0x04, 0x00, 0x04, 0x00,
+	0x00, 0x04, 0x00, 0x04, 0x00, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00, 0x04, 0x04, 0x00, 0x08,
+	0x00, 0x04, 0x00, 0x00, 0x08, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x04, 0x00,
+	// Entry 80 - BF
+	0x00, 0x00, 0x04, 0x00, 0x00, 0x04, 0x00, 0x00,
+	0x00, 0x04, 0x01, 0x00, 0x04, 0x02, 0x00, 0x04,
+	0x00, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0x00, 0x04, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00,
+	0x00, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0x00, 0x08, 0x08, 0x00, 0x00, 0x00, 0x04, 0x00,
+	// Entry C0 - FF
+	0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0x01,
+	0x04, 0x08, 0x04, 0x00, 0x00, 0x00, 0x00, 0x04,
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x04, 0x00, 0x04, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x04, 0x00, 0x05, 0x00, 0x00, 0x00,
+	0x00, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	// Entry 100 - 13F
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00,
+	0x00, 0x00, 0x04, 0x04, 0x00, 0x00, 0x00, 0x04,
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0x08, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x01, 0x00, 0x05, 0x04, 0x00,
+	0x00, 0x04, 0x00, 0x04, 0x04, 0x05, 0x00, 0x00,
+	// Entry 140 - 17F
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00, 0x00,
+} // Size: 381 bytes
+
+var paradigmLocales = [][3]uint16{ // 3 elements
+	0: [3]uint16{0x139, 0x0, 0x7b},
+	1: [3]uint16{0x13e, 0x0, 0x1f},
+	2: [3]uint16{0x3c0, 0x41, 0xee},
+} // Size: 42 bytes
+
+type mutualIntelligibility struct {
+	want     uint16
+	have     uint16
+	distance uint8
+	oneway   bool
+}
+type scriptIntelligibility struct {
+	wantLang   uint16
+	haveLang   uint16
+	wantScript uint8
+	haveScript uint8
+	distance   uint8
+}
+type regionIntelligibility struct {
+	lang     uint16
+	script   uint8
+	group    uint8
+	distance uint8
+}
+
+// matchLang holds pairs of langIDs of base languages that are typically
+// mutually intelligible. Each pair is associated with a confidence and
+// whether the intelligibility goes one or both ways.
+var matchLang = []mutualIntelligibility{ // 113 elements
+	0:   {want: 0x1d1, have: 0xb7, distance: 0x4, oneway: false},
+	1:   {want: 0x407, have: 0xb7, distance: 0x4, oneway: false},
+	2:   {want: 0x407, have: 0x1d1, distance: 0x4, oneway: false},
+	3:   {want: 0x407, have: 0x432, distance: 0x4, oneway: false},
+	4:   {want: 0x43a, have: 0x1, distance: 0x4, oneway: false},
+	5:   {want: 0x1a3, have: 0x10d, distance: 0x4, oneway: true},
+	6:   {want: 0x295, have: 0x10d, distance: 0x4, oneway: true},
+	7:   {want: 0x101, have: 0x36f, distance: 0x8, oneway: false},
+	8:   {want: 0x101, have: 0x347, distance: 0x8, oneway: false},
+	9:   {want: 0x5, have: 0x3e2, distance: 0xa, oneway: true},
+	10:  {want: 0xd, have: 0x139, distance: 0xa, oneway: true},
+	11:  {want: 0x16, have: 0x367, distance: 0xa, oneway: true},
+	12:  {want: 0x21, have: 0x139, distance: 0xa, oneway: true},
+	13:  {want: 0x56, have: 0x13e, distance: 0xa, oneway: true},
+	14:  {want: 0x58, have: 0x3e2, distance: 0xa, oneway: true},
+	15:  {want: 0x71, have: 0x3e2, distance: 0xa, oneway: true},
+	16:  {want: 0x75, have: 0x139, distance: 0xa, oneway: true},
+	17:  {want: 0x82, have: 0x1be, distance: 0xa, oneway: true},
+	18:  {want: 0xa5, have: 0x139, distance: 0xa, oneway: true},
+	19:  {want: 0xb2, have: 0x15e, distance: 0xa, oneway: true},
+	20:  {want: 0xdd, have: 0x153, distance: 0xa, oneway: true},
+	21:  {want: 0xe5, have: 0x139, distance: 0xa, oneway: true},
+	22:  {want: 0xe9, have: 0x3a, distance: 0xa, oneway: true},
+	23:  {want: 0xf0, have: 0x15e, distance: 0xa, oneway: true},
+	24:  {want: 0xf9, have: 0x15e, distance: 0xa, oneway: true},
+	25:  {want: 0x100, have: 0x139, distance: 0xa, oneway: true},
+	26:  {want: 0x130, have: 0x139, distance: 0xa, oneway: true},
+	27:  {want: 0x13c, have: 0x139, distance: 0xa, oneway: true},
+	28:  {want: 0x140, have: 0x151, distance: 0xa, oneway: true},
+	29:  {want: 0x145, have: 0x13e, distance: 0xa, oneway: true},
+	30:  {want: 0x158, have: 0x101, distance: 0xa, oneway: true},
+	31:  {want: 0x16d, have: 0x367, distance: 0xa, oneway: true},
+	32:  {want: 0x16e, have: 0x139, distance: 0xa, oneway: true},
+	33:  {want: 0x16f, have: 0x139, distance: 0xa, oneway: true},
+	34:  {want: 0x17e, have: 0x139, distance: 0xa, oneway: true},
+	35:  {want: 0x190, have: 0x13e, distance: 0xa, oneway: true},
+	36:  {want: 0x194, have: 0x13e, distance: 0xa, oneway: true},
+	37:  {want: 0x1a4, have: 0x1be, distance: 0xa, oneway: true},
+	38:  {want: 0x1b4, have: 0x139, distance: 0xa, oneway: true},
+	39:  {want: 0x1b8, have: 0x139, distance: 0xa, oneway: true},
+	40:  {want: 0x1d4, have: 0x15e, distance: 0xa, oneway: true},
+	41:  {want: 0x1d7, have: 0x3e2, distance: 0xa, oneway: true},
+	42:  {want: 0x1d9, have: 0x139, distance: 0xa, oneway: true},
+	43:  {want: 0x1e7, have: 0x139, distance: 0xa, oneway: true},
+	44:  {want: 0x1f8, have: 0x139, distance: 0xa, oneway: true},
+	45:  {want: 0x20e, have: 0x1e1, distance: 0xa, oneway: true},
+	46:  {want: 0x210, have: 0x139, distance: 0xa, oneway: true},
+	47:  {want: 0x22d, have: 0x15e, distance: 0xa, oneway: true},
+	48:  {want: 0x242, have: 0x3e2, distance: 0xa, oneway: true},
+	49:  {want: 0x24a, have: 0x139, distance: 0xa, oneway: true},
+	50:  {want: 0x251, have: 0x139, distance: 0xa, oneway: true},
+	51:  {want: 0x265, have: 0x139, distance: 0xa, oneway: true},
+	52:  {want: 0x274, have: 0x48a, distance: 0xa, oneway: true},
+	53:  {want: 0x28a, have: 0x3e2, distance: 0xa, oneway: true},
+	54:  {want: 0x28e, have: 0x1f9, distance: 0xa, oneway: true},
+	55:  {want: 0x2a3, have: 0x139, distance: 0xa, oneway: true},
+	56:  {want: 0x2b5, have: 0x15e, distance: 0xa, oneway: true},
+	57:  {want: 0x2b8, have: 0x139, distance: 0xa, oneway: true},
+	58:  {want: 0x2be, have: 0x139, distance: 0xa, oneway: true},
+	59:  {want: 0x2c3, have: 0x15e, distance: 0xa, oneway: true},
+	60:  {want: 0x2ed, have: 0x139, distance: 0xa, oneway: true},
+	61:  {want: 0x2f1, have: 0x15e, distance: 0xa, oneway: true},
+	62:  {want: 0x2fa, have: 0x139, distance: 0xa, oneway: true},
+	63:  {want: 0x2ff, have: 0x7e, distance: 0xa, oneway: true},
+	64:  {want: 0x304, have: 0x139, distance: 0xa, oneway: true},
+	65:  {want: 0x30b, have: 0x3e2, distance: 0xa, oneway: true},
+	66:  {want: 0x31b, have: 0x1be, distance: 0xa, oneway: true},
+	67:  {want: 0x31f, have: 0x1e1, distance: 0xa, oneway: true},
+	68:  {want: 0x320, have: 0x139, distance: 0xa, oneway: true},
+	69:  {want: 0x331, have: 0x139, distance: 0xa, oneway: true},
+	70:  {want: 0x351, have: 0x139, distance: 0xa, oneway: true},
+	71:  {want: 0x36a, have: 0x347, distance: 0xa, oneway: false},
+	72:  {want: 0x36a, have: 0x36f, distance: 0xa, oneway: true},
+	73:  {want: 0x37a, have: 0x139, distance: 0xa, oneway: true},
+	74:  {want: 0x387, have: 0x139, distance: 0xa, oneway: true},
+	75:  {want: 0x389, have: 0x139, distance: 0xa, oneway: true},
+	76:  {want: 0x38b, have: 0x15e, distance: 0xa, oneway: true},
+	77:  {want: 0x390, have: 0x139, distance: 0xa, oneway: true},
+	78:  {want: 0x395, have: 0x139, distance: 0xa, oneway: true},
+	79:  {want: 0x39d, have: 0x139, distance: 0xa, oneway: true},
+	80:  {want: 0x3a5, have: 0x139, distance: 0xa, oneway: true},
+	81:  {want: 0x3be, have: 0x139, distance: 0xa, oneway: true},
+	82:  {want: 0x3c4, have: 0x13e, distance: 0xa, oneway: true},
+	83:  {want: 0x3d4, have: 0x10d, distance: 0xa, oneway: true},
+	84:  {want: 0x3d9, have: 0x139, distance: 0xa, oneway: true},
+	85:  {want: 0x3e5, have: 0x15e, distance: 0xa, oneway: true},
+	86:  {want: 0x3e9, have: 0x1be, distance: 0xa, oneway: true},
+	87:  {want: 0x3fa, have: 0x139, distance: 0xa, oneway: true},
+	88:  {want: 0x40c, have: 0x139, distance: 0xa, oneway: true},
+	89:  {want: 0x423, have: 0x139, distance: 0xa, oneway: true},
+	90:  {want: 0x429, have: 0x139, distance: 0xa, oneway: true},
+	91:  {want: 0x431, have: 0x139, distance: 0xa, oneway: true},
+	92:  {want: 0x43b, have: 0x139, distance: 0xa, oneway: true},
+	93:  {want: 0x43e, have: 0x1e1, distance: 0xa, oneway: true},
+	94:  {want: 0x445, have: 0x139, distance: 0xa, oneway: true},
+	95:  {want: 0x450, have: 0x139, distance: 0xa, oneway: true},
+	96:  {want: 0x461, have: 0x139, distance: 0xa, oneway: true},
+	97:  {want: 0x467, have: 0x3e2, distance: 0xa, oneway: true},
+	98:  {want: 0x46f, have: 0x139, distance: 0xa, oneway: true},
+	99:  {want: 0x476, have: 0x3e2, distance: 0xa, oneway: true},
+	100: {want: 0x3883, have: 0x139, distance: 0xa, oneway: true},
+	101: {want: 0x480, have: 0x139, distance: 0xa, oneway: true},
+	102: {want: 0x482, have: 0x139, distance: 0xa, oneway: true},
+	103: {want: 0x494, have: 0x3e2, distance: 0xa, oneway: true},
+	104: {want: 0x49d, have: 0x139, distance: 0xa, oneway: true},
+	105: {want: 0x4ac, have: 0x529, distance: 0xa, oneway: true},
+	106: {want: 0x4b4, have: 0x139, distance: 0xa, oneway: true},
+	107: {want: 0x4bc, have: 0x3e2, distance: 0xa, oneway: true},
+	108: {want: 0x4e5, have: 0x15e, distance: 0xa, oneway: true},
+	109: {want: 0x4f2, have: 0x139, distance: 0xa, oneway: true},
+	110: {want: 0x512, have: 0x139, distance: 0xa, oneway: true},
+	111: {want: 0x518, have: 0x139, distance: 0xa, oneway: true},
+	112: {want: 0x52f, have: 0x139, distance: 0xa, oneway: true},
+} // Size: 702 bytes
+
+// matchScript holds pairs of scriptIDs where readers of one script
+// can typically also read the other. Each is associated with a confidence.
+var matchScript = []scriptIntelligibility{ // 26 elements
+	0:  {wantLang: 0x432, haveLang: 0x432, wantScript: 0x57, haveScript: 0x1f, distance: 0x5},
+	1:  {wantLang: 0x432, haveLang: 0x432, wantScript: 0x1f, haveScript: 0x57, distance: 0x5},
+	2:  {wantLang: 0x58, haveLang: 0x3e2, wantScript: 0x57, haveScript: 0x1f, distance: 0xa},
+	3:  {wantLang: 0xa5, haveLang: 0x139, wantScript: 0xe, haveScript: 0x57, distance: 0xa},
+	4:  {wantLang: 0x1d7, haveLang: 0x3e2, wantScript: 0x8, haveScript: 0x1f, distance: 0xa},
+	5:  {wantLang: 0x210, haveLang: 0x139, wantScript: 0x2b, haveScript: 0x57, distance: 0xa},
+	6:  {wantLang: 0x24a, haveLang: 0x139, wantScript: 0x4b, haveScript: 0x57, distance: 0xa},
+	7:  {wantLang: 0x251, haveLang: 0x139, wantScript: 0x4f, haveScript: 0x57, distance: 0xa},
+	8:  {wantLang: 0x2b8, haveLang: 0x139, wantScript: 0x54, haveScript: 0x57, distance: 0xa},
+	9:  {wantLang: 0x304, haveLang: 0x139, wantScript: 0x6b, haveScript: 0x57, distance: 0xa},
+	10: {wantLang: 0x331, haveLang: 0x139, wantScript: 0x72, haveScript: 0x57, distance: 0xa},
+	11: {wantLang: 0x351, haveLang: 0x139, wantScript: 0x21, haveScript: 0x57, distance: 0xa},
+	12: {wantLang: 0x395, haveLang: 0x139, wantScript: 0x7d, haveScript: 0x57, distance: 0xa},
+	13: {wantLang: 0x39d, haveLang: 0x139, wantScript: 0x33, haveScript: 0x57, distance: 0xa},
+	14: {wantLang: 0x3be, haveLang: 0x139, wantScript: 0x5, haveScript: 0x57, distance: 0xa},
+	15: {wantLang: 0x3fa, haveLang: 0x139, wantScript: 0x5, haveScript: 0x57, distance: 0xa},
+	16: {wantLang: 0x40c, haveLang: 0x139, wantScript: 0xca, haveScript: 0x57, distance: 0xa},
+	17: {wantLang: 0x450, haveLang: 0x139, wantScript: 0xd7, haveScript: 0x57, distance: 0xa},
+	18: {wantLang: 0x461, haveLang: 0x139, wantScript: 0xda, haveScript: 0x57, distance: 0xa},
+	19: {wantLang: 0x46f, haveLang: 0x139, wantScript: 0x29, haveScript: 0x57, distance: 0xa},
+	20: {wantLang: 0x476, haveLang: 0x3e2, wantScript: 0x57, haveScript: 0x1f, distance: 0xa},
+	21: {wantLang: 0x4b4, haveLang: 0x139, wantScript: 0x5, haveScript: 0x57, distance: 0xa},
+	22: {wantLang: 0x4bc, haveLang: 0x3e2, wantScript: 0x57, haveScript: 0x1f, distance: 0xa},
+	23: {wantLang: 0x512, haveLang: 0x139, wantScript: 0x3b, haveScript: 0x57, distance: 0xa},
+	24: {wantLang: 0x529, haveLang: 0x529, wantScript: 0x38, haveScript: 0x39, distance: 0xf},
+	25: {wantLang: 0x529, haveLang: 0x529, wantScript: 0x39, haveScript: 0x38, distance: 0x13},
+} // Size: 232 bytes
+
+var matchRegion = []regionIntelligibility{ // 15 elements
+	0:  {lang: 0x3a, script: 0x0, group: 0x4, distance: 0x4},
+	1:  {lang: 0x3a, script: 0x0, group: 0x84, distance: 0x4},
+	2:  {lang: 0x139, script: 0x0, group: 0x1, distance: 0x4},
+	3:  {lang: 0x139, script: 0x0, group: 0x81, distance: 0x4},
+	4:  {lang: 0x13e, script: 0x0, group: 0x3, distance: 0x4},
+	5:  {lang: 0x13e, script: 0x0, group: 0x83, distance: 0x4},
+	6:  {lang: 0x3c0, script: 0x0, group: 0x3, distance: 0x4},
+	7:  {lang: 0x3c0, script: 0x0, group: 0x83, distance: 0x4},
+	8:  {lang: 0x529, script: 0x39, group: 0x2, distance: 0x4},
+	9:  {lang: 0x529, script: 0x39, group: 0x82, distance: 0x4},
+	10: {lang: 0x3a, script: 0x0, group: 0x80, distance: 0x5},
+	11: {lang: 0x139, script: 0x0, group: 0x80, distance: 0x5},
+	12: {lang: 0x13e, script: 0x0, group: 0x80, distance: 0x5},
+	13: {lang: 0x3c0, script: 0x0, group: 0x80, distance: 0x5},
+	14: {lang: 0x529, script: 0x39, group: 0x80, distance: 0x5},
+} // Size: 114 bytes
+
+// Total table size 1471 bytes (1KiB); checksum: 4CB1CD46
diff --git a/vendor/golang.org/x/text/language/tags.go b/vendor/golang.org/x/text/language/tags.go
new file mode 100644
index 0000000..42ea792
--- /dev/null
+++ b/vendor/golang.org/x/text/language/tags.go
@@ -0,0 +1,145 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package language
+
+import "golang.org/x/text/internal/language/compact"
+
+// TODO: Various sets of commonly use tags and regions.
+
+// MustParse is like Parse, but panics if the given BCP 47 tag cannot be parsed.
+// It simplifies safe initialization of Tag values.
+func MustParse(s string) Tag {
+	t, err := Parse(s)
+	if err != nil {
+		panic(err)
+	}
+	return t
+}
+
+// MustParse is like Parse, but panics if the given BCP 47 tag cannot be parsed.
+// It simplifies safe initialization of Tag values.
+func (c CanonType) MustParse(s string) Tag {
+	t, err := c.Parse(s)
+	if err != nil {
+		panic(err)
+	}
+	return t
+}
+
+// MustParseBase is like ParseBase, but panics if the given base cannot be parsed.
+// It simplifies safe initialization of Base values.
+func MustParseBase(s string) Base {
+	b, err := ParseBase(s)
+	if err != nil {
+		panic(err)
+	}
+	return b
+}
+
+// MustParseScript is like ParseScript, but panics if the given script cannot be
+// parsed. It simplifies safe initialization of Script values.
+func MustParseScript(s string) Script {
+	scr, err := ParseScript(s)
+	if err != nil {
+		panic(err)
+	}
+	return scr
+}
+
+// MustParseRegion is like ParseRegion, but panics if the given region cannot be
+// parsed. It simplifies safe initialization of Region values.
+func MustParseRegion(s string) Region {
+	r, err := ParseRegion(s)
+	if err != nil {
+		panic(err)
+	}
+	return r
+}
+
+var (
+	und = Tag{}
+
+	Und Tag = Tag{}
+
+	Afrikaans            Tag = Tag(compact.Afrikaans)
+	Amharic              Tag = Tag(compact.Amharic)
+	Arabic               Tag = Tag(compact.Arabic)
+	ModernStandardArabic Tag = Tag(compact.ModernStandardArabic)
+	Azerbaijani          Tag = Tag(compact.Azerbaijani)
+	Bulgarian            Tag = Tag(compact.Bulgarian)
+	Bengali              Tag = Tag(compact.Bengali)
+	Catalan              Tag = Tag(compact.Catalan)
+	Czech                Tag = Tag(compact.Czech)
+	Danish               Tag = Tag(compact.Danish)
+	German               Tag = Tag(compact.German)
+	Greek                Tag = Tag(compact.Greek)
+	English              Tag = Tag(compact.English)
+	AmericanEnglish      Tag = Tag(compact.AmericanEnglish)
+	BritishEnglish       Tag = Tag(compact.BritishEnglish)
+	Spanish              Tag = Tag(compact.Spanish)
+	EuropeanSpanish      Tag = Tag(compact.EuropeanSpanish)
+	LatinAmericanSpanish Tag = Tag(compact.LatinAmericanSpanish)
+	Estonian             Tag = Tag(compact.Estonian)
+	Persian              Tag = Tag(compact.Persian)
+	Finnish              Tag = Tag(compact.Finnish)
+	Filipino             Tag = Tag(compact.Filipino)
+	French               Tag = Tag(compact.French)
+	CanadianFrench       Tag = Tag(compact.CanadianFrench)
+	Gujarati             Tag = Tag(compact.Gujarati)
+	Hebrew               Tag = Tag(compact.Hebrew)
+	Hindi                Tag = Tag(compact.Hindi)
+	Croatian             Tag = Tag(compact.Croatian)
+	Hungarian            Tag = Tag(compact.Hungarian)
+	Armenian             Tag = Tag(compact.Armenian)
+	Indonesian           Tag = Tag(compact.Indonesian)
+	Icelandic            Tag = Tag(compact.Icelandic)
+	Italian              Tag = Tag(compact.Italian)
+	Japanese             Tag = Tag(compact.Japanese)
+	Georgian             Tag = Tag(compact.Georgian)
+	Kazakh               Tag = Tag(compact.Kazakh)
+	Khmer                Tag = Tag(compact.Khmer)
+	Kannada              Tag = Tag(compact.Kannada)
+	Korean               Tag = Tag(compact.Korean)
+	Kirghiz              Tag = Tag(compact.Kirghiz)
+	Lao                  Tag = Tag(compact.Lao)
+	Lithuanian           Tag = Tag(compact.Lithuanian)
+	Latvian              Tag = Tag(compact.Latvian)
+	Macedonian           Tag = Tag(compact.Macedonian)
+	Malayalam            Tag = Tag(compact.Malayalam)
+	Mongolian            Tag = Tag(compact.Mongolian)
+	Marathi              Tag = Tag(compact.Marathi)
+	Malay                Tag = Tag(compact.Malay)
+	Burmese              Tag = Tag(compact.Burmese)
+	Nepali               Tag = Tag(compact.Nepali)
+	Dutch                Tag = Tag(compact.Dutch)
+	Norwegian            Tag = Tag(compact.Norwegian)
+	Punjabi              Tag = Tag(compact.Punjabi)
+	Polish               Tag = Tag(compact.Polish)
+	Portuguese           Tag = Tag(compact.Portuguese)
+	BrazilianPortuguese  Tag = Tag(compact.BrazilianPortuguese)
+	EuropeanPortuguese   Tag = Tag(compact.EuropeanPortuguese)
+	Romanian             Tag = Tag(compact.Romanian)
+	Russian              Tag = Tag(compact.Russian)
+	Sinhala              Tag = Tag(compact.Sinhala)
+	Slovak               Tag = Tag(compact.Slovak)
+	Slovenian            Tag = Tag(compact.Slovenian)
+	Albanian             Tag = Tag(compact.Albanian)
+	Serbian              Tag = Tag(compact.Serbian)
+	SerbianLatin         Tag = Tag(compact.SerbianLatin)
+	Swedish              Tag = Tag(compact.Swedish)
+	Swahili              Tag = Tag(compact.Swahili)
+	Tamil                Tag = Tag(compact.Tamil)
+	Telugu               Tag = Tag(compact.Telugu)
+	Thai                 Tag = Tag(compact.Thai)
+	Turkish              Tag = Tag(compact.Turkish)
+	Ukrainian            Tag = Tag(compact.Ukrainian)
+	Urdu                 Tag = Tag(compact.Urdu)
+	Uzbek                Tag = Tag(compact.Uzbek)
+	Vietnamese           Tag = Tag(compact.Vietnamese)
+	Chinese              Tag = Tag(compact.Chinese)
+	SimplifiedChinese    Tag = Tag(compact.SimplifiedChinese)
+	TraditionalChinese   Tag = Tag(compact.TraditionalChinese)
+	Zulu                 Tag = Tag(compact.Zulu)
+)