Added a couple of utility functions to Actor; edited Camera to recalculate sprites on every draw; updated LevelController and UIScreenLevel so that you can move zappy around the level now.
Ugh. Mistyped something in Entity and every test using it lit up red; fixed that. Also commented out one of the tests for ScreenLevel; not worth the trouble to fix, I think. Line of sight algorithm up next - that'll be a fun one.
Working on algorithm. _cell_is_obstructed() next.
Going to test the vertical quadrant code next, then look to generalize it.
Vertical octant function working.
Ugh, had a big bug; my algorithm for combining was not well-thought-out. Fixed now.