cappuccino/execute_ctrl: allow mfspr to stall the pipeline
cappuccino/rf: fix typo in comment
cappuccino/execute_ctrl: whitespace cleanup
cappuccino/ctrl: whitespace cleanup
cappuccino/ctrl: account for stalls in ctrl stage when stepping
cappuccino: flush ctrl and wb stages on pipeline_flush

The only exception is on a debug unit stall, where
we want the instruction to fulfill it's execution.