rev-liquidprompt: change git diff counter behavior

This reverts commit d002897bedc22f817a08f86f95229da3e7d22a5a.
lp: in git show line changes only from work tree

The insertions/deletions counter will show only the
difference between index and work tree, not between
last commit and work tree.
lp: remove api for 256 colours support

If the terminal exhibits the capability to handle
256 colours then the liquidprompt still supports
this feature by setting the desired colour number
for each colour declaration.
lp: remove debug time

It was accidentally committed after an update
of liquidprompt with the upstream
lp: refactor default liquidprompt theme
lp: synchronisation between liquidprompt files

Add missing variables and default values
lp: Add prompt mark prefix feature

In theme file the prompt mark is printed
in separate line.
lp: disable load feature
git: add alias for adding to index in patch mode