Pre-Alpha 4.4

Made some major changes to how sprites are handled. They're now on a
spritesheet system instead. Added chasms, an event system for floors,
and some other stuff. I did a bunch of bugfixes, mostly dealing with
clarifying tooltips, etc. There are a couple of new monsters but they're
not in the game yet, and I also replaced the spawntable system with a
new system that uses xml to determine spawn tables. A much-needed
improvement.