sim-fast-core: initial commit.

	modified:   simavr/sim/run_avr.c
	new file:   simavr/sim/sim_fast_core.c
	new file:   simavr/sim/sim_fast_core.h
	new file:   simavr/sim/sim_fast_core_profiler.c
	new file:   simavr/sim/sim_fast_core_profiler.h