After experimenting with a long running average at maxed out FPS and a variety of map sizes, 128 seems to actually be a good size to use if only drawing bits of world with stuff in it. 64 actually did even better in some situations, but significantly worse in others (lots of land, zoomed out).

frontlib refactoring socket.h now completely wraps all the lowlevel neworking, so it would be easy to switch away from SDL_net if needed. Also reduced global state by making an IPC connection an object-like thing.

Only create textures for non-empty LandPixel chunks. This should save a fair amount of memory, especially on smaller maps, and eliminate a number of draws