Updated branding and documentation.  Expanded domain knowledge for ice and force floor tiles.

I noticed that some levels in the classical levelset wouldn't solve due to missing or incorrect domain knowledge, which I fixed.

I also changed how actions with ice-wall tiles are defined: the player will change slide direction when slipping onto the tile, not when slipping off the tile.  This reduces the total number of action definitions because there are fewer ways to move (or slip or slide) to an ice-wall than from an ice-wall, and it has the added benefit that overall, ice-wall action definitions are simpler.

For posterity, I updated the branding and documentation.