Remove numerous warnings from bitflags! expanding to non-uppercase static constants.
Merge pull request #10 from amw-zero/bitflag_warnings

Remove numerous warnings from bitflags! expanding to non-uppercase static constants.
compiler fixes, static -> const
DEX instruction and test
beef up test
Rebase onto master to pick up compiler errors and use load_x_register to simplify impl of dec_x. Because load_x_register sets the zero and negative status flags already
pull in the remote version of decrement-x branch? So I can push to it? I have no idea what I'm doing