surf_screen and t_frame are globals; stopped passing them as arguments.
started factoring out global t_frame
Updated collide to take two sprites. removed references to stdint.h (using inttypes.h where necessary). Makefile: update header dependencies.
* mt.c: Added (Mersenne Twister random number generator). * sound.h: moved #defines out to here, used them in main.c. * dust.c: moved space dust functions out to here.