Turbo boost the turbo boost mode

I had left a debugging try/catch wrapper around each simulated 8080
instruction.  Taking this out means lower CPU load, and in unregulated
mode, means about 2.5x faster operation.

Also, I made it so the "--empty--" choice in the disk pulldown box is
not selectable if the drive is already empty.

Hid a few unnecessary configuration globals in ccemu.js

Finally, I got rid of some encapsulation breakage by having an official
way to inspect the CPU register state from outside the CPU module.