Revert "try to make hg also work [does not work yet]"

This reverts commit be7b4d31072ef66fdd5af09248064bc51770bc7d.
remove old hg part from staging diff
Allow to revert staged hunks
do not need separate variables for reversing and staging
stage hunk mapping waited for another keypress, fix that
Merge commit '6757'
Merge commit 'e6e636'
Merge commit '2470'