Microwatt goes multiprocessor

It's been awhile since we dropped in on Microwatt , the OpenPOWER VHDL softcore. Microwatt now runs on multiple FPGA boards or can be run (slowly) in simulation, and is capable of booting Linux. Raptor uses Microwatt for the Arctic Tern soft BMC . Although it still doesn't support vector instructions, recent commits have added an FPU and many of the standard special-purpose registers, and the…