Now it's up to 99% tests passing, 15362 are still failing, but many
of those are the unimplemented IN/OUT instructions, which the Genesis
doesn't seem to use
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
Mortal Kombat 2 was working but somewhere while getting the harte
tests to work, I fixed interrupts to change the flags before they're
pushed to the stack, in order to match the expected behaviour from
the tests when an address error occurs (sr is changed and the stack
push causes the error). I correctly saved the state of sr in the
function for group0 interrupts, to push to the stack later, but the
normal interrupts was saving sr *after* the flags were changed...
Now it saves sr beforehand
I also included some changes to the gfx interface to allow taking
frames, to fix a compile error introduced by the last commit.
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
