diff --git a/vendor/github.com/rivo/uniseg/grapheme.go b/vendor/github.com/rivo/uniseg/grapheme.go
new file mode 100644
index 0000000..fbb846b
--- /dev/null
+++ b/vendor/github.com/rivo/uniseg/grapheme.go
@@ -0,0 +1,258 @@
+package uniseg
+
+// The states of the grapheme cluster parser.
+const (
+	grAny = iota
+	grCR
+	grControlLF
+	grL
+	grLVV
+	grLVTT
+	grPrepend
+	grExtendedPictographic
+	grExtendedPictographicZWJ
+	grRIOdd
+	grRIEven
+)
+
+// The grapheme cluster parser's breaking instructions.
+const (
+	grNoBoundary = iota
+	grBoundary
+)
+
+// The grapheme cluster parser's state transitions. Maps (state, property) to
+// (new state, breaking instruction, rule number). The breaking instruction
+// always refers to the boundary between the last and next code point.
+//
+// This map is queried as follows:
+//
+//   1. Find specific state + specific property. Stop if found.
+//   2. Find specific state + any property.
+//   3. Find any state + specific property.
+//   4. If only (2) or (3) (but not both) was found, stop.
+//   5. If both (2) and (3) were found, use state and breaking instruction from
+//      the transition with the lower rule number, prefer (3) if rule numbers
+//      are equal. Stop.
+//   6. Assume grAny and grBoundary.
+var grTransitions = map[[2]int][3]int{
+	// GB5
+	{grAny, prCR}:      {grCR, grBoundary, 50},
+	{grAny, prLF}:      {grControlLF, grBoundary, 50},
+	{grAny, prControl}: {grControlLF, grBoundary, 50},
+
+	// GB4
+	{grCR, prAny}:        {grAny, grBoundary, 40},
+	{grControlLF, prAny}: {grAny, grBoundary, 40},
+
+	// GB3.
+	{grCR, prLF}: {grAny, grNoBoundary, 30},
+
+	// GB6.
+	{grAny, prL}: {grL, grBoundary, 9990},
+	{grL, prL}:   {grL, grNoBoundary, 60},
+	{grL, prV}:   {grLVV, grNoBoundary, 60},
+	{grL, prLV}:  {grLVV, grNoBoundary, 60},
+	{grL, prLVT}: {grLVTT, grNoBoundary, 60},
+
+	// GB7.
+	{grAny, prLV}: {grLVV, grBoundary, 9990},
+	{grAny, prV}:  {grLVV, grBoundary, 9990},
+	{grLVV, prV}:  {grLVV, grNoBoundary, 70},
+	{grLVV, prT}:  {grLVTT, grNoBoundary, 70},
+
+	// GB8.
+	{grAny, prLVT}: {grLVTT, grBoundary, 9990},
+	{grAny, prT}:   {grLVTT, grBoundary, 9990},
+	{grLVTT, prT}:  {grLVTT, grNoBoundary, 80},
+
+	// GB9.
+	{grAny, prExtend}: {grAny, grNoBoundary, 90},
+	{grAny, prZWJ}:    {grAny, grNoBoundary, 90},
+
+	// GB9a.
+	{grAny, prSpacingMark}: {grAny, grNoBoundary, 91},
+
+	// GB9b.
+	{grAny, prPreprend}: {grPrepend, grBoundary, 9990},
+	{grPrepend, prAny}:  {grAny, grNoBoundary, 92},
+
+	// GB11.
+	{grAny, prExtendedPictographic}:                     {grExtendedPictographic, grBoundary, 9990},
+	{grExtendedPictographic, prExtend}:                  {grExtendedPictographic, grNoBoundary, 110},
+	{grExtendedPictographic, prZWJ}:                     {grExtendedPictographicZWJ, grNoBoundary, 110},
+	{grExtendedPictographicZWJ, prExtendedPictographic}: {grExtendedPictographic, grNoBoundary, 110},
+
+	// GB12 / GB13.
+	{grAny, prRegionalIndicator}:    {grRIOdd, grBoundary, 9990},
+	{grRIOdd, prRegionalIndicator}:  {grRIEven, grNoBoundary, 120},
+	{grRIEven, prRegionalIndicator}: {grRIOdd, grBoundary, 120},
+}
+
+// Graphemes implements an iterator over Unicode extended grapheme clusters,
+// specified in the Unicode Standard Annex #29. Grapheme clusters correspond to
+// "user-perceived characters". These characters often consist of multiple
+// code points (e.g. the "woman kissing woman" emoji consists of 8 code points:
+// woman + ZWJ + heavy black heart (2 code points) + ZWJ + kiss mark + ZWJ +
+// woman) and the rules described in Annex #29 must be applied to group those
+// code points into clusters perceived by the user as one character.
+type Graphemes struct {
+	// The code points over which this class iterates.
+	codePoints []rune
+
+	// The (byte-based) indices of the code points into the original string plus
+	// len(original string). Thus, len(indices) = len(codePoints) + 1.
+	indices []int
+
+	// The current grapheme cluster to be returned. These are indices into
+	// codePoints/indices. If start == end, we either haven't started iterating
+	// yet (0) or the iteration has already completed (1).
+	start, end int
+
+	// The index of the next code point to be parsed.
+	pos int
+
+	// The current state of the code point parser.
+	state int
+}
+
+// NewGraphemes returns a new grapheme cluster iterator.
+func NewGraphemes(s string) *Graphemes {
+	g := &Graphemes{}
+	for index, codePoint := range s {
+		g.codePoints = append(g.codePoints, codePoint)
+		g.indices = append(g.indices, index)
+	}
+	g.indices = append(g.indices, len(s))
+	g.Next() // Parse ahead.
+	return g
+}
+
+// Next advances the iterator by one grapheme cluster and returns false if no
+// clusters are left. This function must be called before the first cluster is
+// accessed.
+func (g *Graphemes) Next() bool {
+	g.start = g.end
+
+	// The state transition gives us a boundary instruction BEFORE the next code
+	// point so we always need to stay ahead by one code point.
+
+	// Parse the next code point.
+	for g.pos <= len(g.codePoints) {
+		// GB2.
+		if g.pos == len(g.codePoints) {
+			g.end = g.pos
+			g.pos++
+			break
+		}
+
+		// Determine the property of the next character.
+		nextProperty := property(g.codePoints[g.pos])
+		g.pos++
+
+		// Find the applicable transition.
+		var boundary bool
+		transition, ok := grTransitions[[2]int{g.state, nextProperty}]
+		if ok {
+			// We have a specific transition. We'll use it.
+			g.state = transition[0]
+			boundary = transition[1] == grBoundary
+		} else {
+			// No specific transition found. Try the less specific ones.
+			transAnyProp, okAnyProp := grTransitions[[2]int{g.state, prAny}]
+			transAnyState, okAnyState := grTransitions[[2]int{grAny, nextProperty}]
+			if okAnyProp && okAnyState {
+				// Both apply. We'll use a mix (see comments for grTransitions).
+				g.state = transAnyState[0]
+				boundary = transAnyState[1] == grBoundary
+				if transAnyProp[2] < transAnyState[2] {
+					g.state = transAnyProp[0]
+					boundary = transAnyProp[1] == grBoundary
+				}
+			} else if okAnyProp {
+				// We only have a specific state.
+				g.state = transAnyProp[0]
+				boundary = transAnyProp[1] == grBoundary
+				// This branch will probably never be reached because okAnyState will
+				// always be true given the current transition map. But we keep it here
+				// for future modifications to the transition map where this may not be
+				// true anymore.
+			} else if okAnyState {
+				// We only have a specific property.
+				g.state = transAnyState[0]
+				boundary = transAnyState[1] == grBoundary
+			} else {
+				// No known transition. GB999: Any x Any.
+				g.state = grAny
+				boundary = true
+			}
+		}
+
+		// If we found a cluster boundary, let's stop here. The current cluster will
+		// be the one that just ended.
+		if g.pos-1 == 0 /* GB1 */ || boundary {
+			g.end = g.pos - 1
+			break
+		}
+	}
+
+	return g.start != g.end
+}
+
+// Runes returns a slice of runes (code points) which corresponds to the current
+// grapheme cluster. If the iterator is already past the end or Next() has not
+// yet been called, nil is returned.
+func (g *Graphemes) Runes() []rune {
+	if g.start == g.end {
+		return nil
+	}
+	return g.codePoints[g.start:g.end]
+}
+
+// Str returns a substring of the original string which corresponds to the
+// current grapheme cluster. If the iterator is already past the end or Next()
+// has not yet been called, an empty string is returned.
+func (g *Graphemes) Str() string {
+	if g.start == g.end {
+		return ""
+	}
+	return string(g.codePoints[g.start:g.end])
+}
+
+// Bytes returns a byte slice which corresponds to the current grapheme cluster.
+// If the iterator is already past the end or Next() has not yet been called,
+// nil is returned.
+func (g *Graphemes) Bytes() []byte {
+	if g.start == g.end {
+		return nil
+	}
+	return []byte(string(g.codePoints[g.start:g.end]))
+}
+
+// Positions returns the interval of the current grapheme cluster as byte
+// positions into the original string. The first returned value "from" indexes
+// the first byte and the second returned value "to" indexes the first byte that
+// is not included anymore, i.e. str[from:to] is the current grapheme cluster of
+// the original string "str". If Next() has not yet been called, both values are
+// 0. If the iterator is already past the end, both values are 1.
+func (g *Graphemes) Positions() (int, int) {
+	return g.indices[g.start], g.indices[g.end]
+}
+
+// Reset puts the iterator into its initial state such that the next call to
+// Next() sets it to the first grapheme cluster again.
+func (g *Graphemes) Reset() {
+	g.start, g.end, g.pos, g.state = 0, 0, 0, grAny
+	g.Next() // Parse ahead again.
+}
+
+// GraphemeClusterCount returns the number of user-perceived characters
+// (grapheme clusters) for the given string. To calculate this number, it
+// iterates through the string using the Graphemes iterator.
+func GraphemeClusterCount(s string) (n int) {
+	g := NewGraphemes(s)
+	for g.Next() {
+		n++
+	}
+	return
+}