Fixed Issue #288: The Award Screen "Speed Up" Key Bug

This fix creates a very minor issue: the game speed wont be set to its
"Speed Up" state when a player is still holding down the "Speed Up" key
when they have closed the award screen and it has unpaused the game.

They can then resume the "Speed Up" speed state by releasing the "Speed
Up" key and then pressing it again.

I've created a commit which fixes this issue for ASCII keyboards which
don't require UI:OnKeyUp() to provide UTF-8 key codes, which it currently
can't provide with the supported SDL version. So I'm not going to publish
this commit until OnKeyUp() supports UTF-8 keycodes because the missing
support for UTF keycodes would prevent the "Speed Up" game speed state from
being disabled.