Special thanks to raddad772 https://github.com/raddad772
Also added some fixes to the Z80 for panicking math operations, but
it still won't complete due to an unimplemented instruction
I wanted to make this a bit more modular, so it's easier in theory to
write external crates that can reuse bits, and selectively compile in
bits, such as adding new systems or new cpu implementations
Some debug code was enabled that prevented illegal instructions
from being handled normally with a processor exception
The brief instruction word decoding could cause an illegal instruction
if it didn't match the docs, but the actual implementation would not
complain in those cases, so I modified it to not perform validation
for <=MC68010
Increment and Decrement addressing modes, when using the stack pointer,
will always inc/dec by at least 2 bytes, even if it's a byte operation,
to keep the stack aligned to the nearest word boundary
