keymap filter by keybindings in the userpreferences.
- optional, select between name/keybinding.
- when key input can't be parsed, alert red to give the user some feedback.
- key shortcut parsing could be improved or swapped out for button which grabs shortcut.


git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@54951 954f8c5b-7b00-dc11-b283-0030488c597c