Update the C tools to match pokered and pokecrystal #122
Description
The current pokered and pokecrystal repos have very different C tools than pokegold-spaceworld. They're refactored to all use a single common.h header file for shared functions, and various bugs have been fixed as well. (For example, tools/gfx.c is capable of segfaulting, which I've never seen in pokecrystal.)