Squashed 'bundle/vimproc.vim/' changes from 21a79bf..3e05502

3e05502 Fix example
421b303 Update documentation
3ea27b7 Merge pull request #170 from ichizok/fix-vp_kill
75101c4 Fixed vp_kill; kill pgid only if pid == pgid

git-subtree-dir: bundle/vimproc.vim
git-subtree-split: 3e055023dfab4f5a4dfa05a834f9d0cb7294a82e
Merge commit '80d7e4dfb76eab8e8ce49f6a2240062afad70fab'