Map Editor!

So... Painted a couple of new background plates. Fixed some bad sprite coordinates and cleaned up my keyboard mapping quite a lot.

Broke the move countdown clock. C'est la vie.

But the real big news? First light on my level editor! Access it with the "e" key. No, you can't exit it, at this point. Had to convert all my pixel references to cell refs. However, this is going to be crucial for tuning the game (assuming I get that far). Right now, you can place the heroine (with "h" key), move the cursor around, add items from the palette (keys 1-6) and delete them with the Delete key (crazy, I know...). Want to add the ability to move things around, better palette choosing and a way to save the new masterpiece. At that point, should be about done.

Also did some philosophical heavy lifting on how stages and overlays should work.