xinitrc: further ctrl/compose key migration

- Make Capslock an additional Ctrl key (to ease Ctrl migration)
- Map Compose to the Menu key
- Make the keypad print a . instead of a ,
- Also we don't have a Capslock anymore, so in case we broke things by
  accidentally pressing Capslock before changing the keymap, make Shift
  return to non-Capslocked state.

Also remove old capslock-compose script which is not needed anymore.