Automatically assign menu keys based on name, alternative to pressing number 0-9 on menus items.
keys are assigned by first giving each menu item the first character of any word, if that fails any key in the name is used.
- active key is shown underlined.
- only ascii keys are assigned currently.
- can run operators, open menu items.
- currently this only works in cases where number buttons were used (UI_BLOCK_NUMSELECT), but could be enabled for file menu, splash etc by removing this check.