_git: completion updates including up to git 1.8.2 changelog part 2
_git: add 'submodule deinit' command
_git: add new configuration options
_git: git config options: reword TODO to reflect missing merge/diff/filter drivers
_git: support completing remote branches without <remote>/ prefix

this is used in git 1.8's
git checkout <branch>
as a shorthand for
git checkout -b <branch> --track <remote>/<branch>
in case <branch> exists on exactly one remote and is not a local branch
SPELLING