Merge branch 'maint' of git://repo.or.cz/git-gui into maint

Merge branch 'maint' of git://repo.or.cz/git-gui into maint

* 'maint' of git://repo.or.cz/git-gui:
  git-gui: Work around bad interaction between Tcl and cmd.exe on ^{tree}
  git-gui: Don't linewrap within console windows
  git-gui: Correct ls-tree buffering problem in browser
  git-gui: Skip nicknames when selecting author initials
  git-gui: Ensure windows shortcuts always have .bat extension
  git-gui: Include a Push action on the left toolbar
  git-gui: Bind M1-P to push action
  git-gui: Don't bind F5/M1-R in all windows
  git-gui: Unlock the index when cancelling merge dialog
  git-gui: properly popup error if gitk should be started but is not installed