Squashed 'git-bash-completion/' content from commit d1d2502

git-subtree-dir: git-bash-completion
git-subtree-split: d1d25024c4a68f7724a1876598664f13c01aac19
Merge commit 'c82d520049f7bc116105af4f2c92e8fc0f86423f' as 'git-bash-completion'
Add git completion as subtree