Sprites and exiting

Implemented the chip sprite for easy flipping and highlighting, and had
them show up onscreen. Next move might be a rewrite of the windowing
system using clanlibs guimanager rather than the more primitive
clan_display setup. It'll take some work to get my head around it, but
until I do, I can't interact very much with the player. However, no
weird compiling errors and the game mechanics are untouched.