state, map: use keycodes only for the API functions The policy is now consistent: every API functions which recieves a keycode should resolve it to an xkb_key first thing, and all the internal functions use that instead of the keycode. To facilitate it a bit, we move the KeycodeInRange check to XkbKey itself, which returns NULL if the keycode is illegal. Signed-off-by: Ran Benita <ran234@gmail.com>