Added a way to get a framebuffer interface for a window, and also a way to create a software renderer for an arbitrary surface. The software renderer has been re-routed to use the framebuffer interface, which makes it possible to have software rendering available even on simple ports.

/*
 *	common.h
 *	written by Holmes Futrell
 *	use however you want
 */

#define SCREEN_WIDTH 320
#define SCREEN_HEIGHT 480

extern int randomInt(int min, int max);
extern float randomFloat(float min, float max);
extern void fatalError(const char *string);