Compute lines of *unstaged* changes in prompt
Compute lines of *unstaged* changes in prompt

Parse `git diff --shortstat` to get the line count of *unstaged* changes.

Improvements of the git related stuff are still possible, using more
plumbing commands, like:
* `git diff-index --quiet HEAD` to check for uncommitted changes (branch
  color), rather than relying on the `git diff --shortstat HEAD`
* `git ls-files --exclude-standard --others` to check for untracked
  files

pkkolos/liquidprompt,illwieckz/liquidprompt,joshuarubin/dotfiles,elementalvoid/liquidprompt,enrdstrm/liquidprompt,smadhueagle/liquidprompt,jaesivsm/liquidprompt,dpilone/liquidprompt,mathieumd/liquidprompt,colinlieberman/liquidprompt,alexprengere/liquidprompt,dtschan/liquidprompt,jonathanjsimon/liquidprompt,lyoshenka/liquidprompt,tkuminecz/liquidprompt,timhyson/liquidprompt,nojhan/liquidprompt,kenrachynski/liquidprompt,BobHood/liquidprompt,tocomo/liquidprompt,joshuarubin/dotfiles,joshuarubin/dotfiles,dan-cleinmark/liquidprompt,joshuarubin/dotfiles,tsbarnes/liquidprompt,milouse/liquidprompt,tstone2077/liquidprompt,laurentbardin/liquidprompt