Clean up imports

manifest_xml: import `HEAD` and `R_HEADS` from correct module
version: import `HEAD` from correct module

`HEAD` and `R_HEADS` should be imported from the git_refs module,
where they are originally defined, rather than from the project
module.

repo: remove unused import of readline

cherry_pick: import standard modules on separate lines
smartsync: import subcmd modules explicitly from subcmd

Use:
  `import re
  import sys`
and
  `from subcmds.sync import Sync`

Instead of:
  `import sys, re`
and
  `from sync import Sync`

Change-Id: Ie10dd6832710939634c4f5c86b9ba5a9cd6fc92e
diff --git a/manifest_xml.py b/manifest_xml.py
index 8e9efd1..f4f6a75 100644
--- a/manifest_xml.py
+++ b/manifest_xml.py
@@ -21,7 +21,8 @@
 import xml.dom.minidom
 
 from git_config import GitConfig
-from project import RemoteSpec, Project, MetaProject, R_HEADS, HEAD
+from git_refs import R_HEADS, HEAD
+from project import RemoteSpec, Project, MetaProject
 from error import ManifestParseError
 
 MANIFEST_FILE_NAME = 'manifest.xml'
diff --git a/repo b/repo
index d6b46c8..f540cbb 100755
--- a/repo
+++ b/repo
@@ -88,7 +88,6 @@
 import optparse
 import os
 import re
-import readline
 import subprocess
 import sys
 import urllib2
diff --git a/subcmds/cherry_pick.py b/subcmds/cherry_pick.py
index 7890af4..7a6d4c2 100644
--- a/subcmds/cherry_pick.py
+++ b/subcmds/cherry_pick.py
@@ -13,7 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import sys, re
+import re
+import sys
 from command import Command
 from git_command import GitCommand
 
diff --git a/subcmds/smartsync.py b/subcmds/smartsync.py
index 1edbd35..e164859 100644
--- a/subcmds/smartsync.py
+++ b/subcmds/smartsync.py
@@ -13,7 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from sync import Sync
+from subcmds.sync import Sync
 
 class Smartsync(Sync):
   common = True
diff --git a/subcmds/version.py b/subcmds/version.py
index 03195f8..243e367 100644
--- a/subcmds/version.py
+++ b/subcmds/version.py
@@ -16,7 +16,7 @@
 import sys
 from command import Command, MirrorSafeCommand
 from git_command import git
-from project import HEAD
+from git_refs import HEAD
 
 class Version(Command, MirrorSafeCommand):
   wrapper_version = None