Squashed 'bundle/vim-shell/' content from commit 4adb4ad

git-subtree-dir: bundle/vim-shell
git-subtree-split: 4adb4ad2fdf9a132ea366cc1dca998721a8bddf0
Merge commit 'e2e9b13696d94031b8946ec59fe4948284b473f6' as 'bundle/vim-shell'