gdk: Redo key events

gdk: Redo key events

Add all of the keyboard translation results in the key event,
so we can translate the keyboard state at the time the event
is created, and avoid doing state translation at match time.

We actually need to carry two sets of translation results,
since we ignore CapsLock when matching accelerators, in
gdk_event_matches().

At the same time, drop the scancode field - it is only ever
set on win32, and is basically unused in GTK.

Update all callers.