Merge branch 'bp/git-gui-bind-kp-enter'

"git gui" performs commit upon CTRL/CMD+ENTER but the
CTRL/CMD+KP_ENTER (i.e. enter key on the numpad) did not have the
same key binding.  It now does.

* bp/git-gui-bind-kp-enter:
  git-gui: bind CTRL/CMD+numpad ENTER to do_commit