Save IFS at startup to restore it in _lp_set_prompt

We already restore IFS to its default value. This patch only changes the
way it is done to avoid a call to 'echo' in a sub-shell at runtime.
Fixes #267.
"hg outgoing" is slow, so diabled. closes #217
Correct the analog hour calculation.

 "date %I" returns a number between 1 and 12 and we want 12 to be 0.
RUNTIME: minor optimization
Counting git unpushed commit