bootstrapping, ints to unsigned, mul, refinements, video out.

rudimentry bootstrapper/compiler started.

a few use of signed types changed to unsigned,
	mainly immediate load functions.

mul(tiply) added.

beginnings of functioning video out.

mov refinements...  properly fetch immediate operand values.

immediate fetcher functions refined...  try to ensure a platform
	agnostic immediate operand fetch.

	modified:   Makefile
	modified:   src/vm_run_thread.c
	modified:   src/vm_run_thread.h
	modified:   src/vm_sdl_main.c