Rewrite of renderer, untested
Split out microcode; synthesizes, hasn't been tested

Microcode containing regfile and alu has now been converted into
cpu containing microcode, registers, regfile and alu, glued together
by a few muxes. Hopefully this is a slightly more logical layout.

Synthesis is sucessful (check timing, micro -> rf -> alu out), but
it has not been simulated nor implemented yet.