fix #207: mark play.html/standalone.html as UTF-8
fix #219: don't cancel edit mode when a message displays.
fix #221: make backup/restore keep camera stable when player disappears.
fix #211: unfocus code panel when cmd-clicking level.
fix #239: don't process more realtime ticks if we won.
fix #228: don't clear messagetext-- it makes us go to the next level.

I can't figure out how to write a test for this, since tests interact
strangely with the level state machine.
fix accidental global variable
Merge pull request #251 from rmmh/master

bugfix