Tutorial [Alpha 21]

This update adds a tutorial dungeon before you get to the title screen. It has no text or prompts for now, but is simple enough to show newbies what the game is about.

I've also fixed a few minor bugs.

The tutorial is made from maps made in the editor. This lets me make new dungeons from premade maps. I have in mind a beginner's dungeon that's a bit less taxing than Ending, but themed around hooks and snaking room placement. This will replace the Thief dungeon (which I still haven't fully figured out) and give me space to build a new puzzle campaign.