Making key up events implicit was sort-of a nice idea, but it's too
tricky and unreliable and makes the key lookup code (interpret_keys())
hard to reason about. See e.g. previous commit for subtle bugs and
issues this caused.
Make key-up events explicit instead. Add key up events to all VOs.
Any time MP_KEY_STATE_DOWN is used, the matching key up event must
use MP_KEY_STATE_UP.
Rewrite the key lookup code. It should be simpler and more robust now.
(Even though the LOC increases, because the new code is less "compact".)
wm4
c4766dc3c6