Avoid using atexit()

[takkaria]

A couple of places in the code currently use this -- fix them.

[d_m]

Would an OK resolution be to move the hooks into quit() in z-util.c? It looks like main() from main.c calls quit() at the end, and it seems like most of the other points out of the game call quit().

There are some places where exit() is called directly but we should probably quit. Assuming this resolution seems OK, I'll fix those up too.

[d_m]

From IRC:

< takkaria> no, that isn't the right behaviour either < takkaria> the point here is to have alloc/dealloc functions which are called in the right places rather than exit() or quit() dealign with it < takkaria> it's part of a broader change, really, to try and init whole-game stuff and per-game stuff so at some point we can make new characters and load new savefiles while running without causing memory eaks