Too exhausted to go into detail right now, but...

New title music thanks to @Matt Heritage. Also got it looping (thanks for fixing that long-standing bug, Mozilla).

Can now lay down floor in level editor. Hero (Andy) respects floors now, won't move without 'em. Got floor edges working and being auto-applied in level editor.

Level editor delete can now remove other objects at location if you hold down "shift" too. This is so you can remove bad floor tiles.

Now loading levels from %data.js auxiliary file and can dump them from level editor.

A reasonable amount done today all told, I think.