Still working on audio

Well, I finally gave up (for now, at least) waiting on eKid's audio library, and instead used a new library (LIBXM7) that sverx from the gbadev forums recently released. And it works perfectly -- well, on the emulator. I thought it worked right on hardware, but turns out I was using the wrong build. So there's more work to do -- either waiting on eKid, or getting this LIBXM7 to work right on hardware....