BattleClass is no longer an enum
Instead, it is a configurable, cached class so that anyone can implement whatever BattleClasses they want to
Added the ability to have multiple canvases for tiles
Still need to finish up Powerups
Sounds have been delegated to spells and items instead of the dumb system we had before
Additionally, AssetLoader now has a void playSound(String) method rather than a Sound getSound(String) method that just automatically plays the sound
Still need to finish up Powerups
Removed a random TODO
Powerups should work now
Theoretically, everything should be done with the core, and be 100% configurable
Next step: the editor