Brings the CheckerCPU back to life to allow FS and SE checking of the
O3CPU. These changes have only been tested with the ARM ISA. Other
ISAs potentially require modification.
A whole bunch of stuff has been converted to use the new params stuff, but
the CPU wasn't one of them. While we're at it, make some things a bit
more stylish. Most of the work was done by Gabe, I just cleaned stuff up
a bit more at the end.