Rewrote very nearly the entire database backend.

The only way to load anything that I'm supporting now is the load_board method. It incidentally loads everything a board depends on: spots, places, and so on.

*Saving* things may not be so limited--I think it would be sensible to rely on the game state manager thingus to tell the database what objects have changed, and for the database backend to thence save all those in a batch.