MacOS X AudioUnit instrument wrapper for mt32emu

Hello.

I created a MacOS X AudioUnit instrument using mt32emu, which can be used as a software instrument in software like GarageBand, Logic, Ableton Live and any other Mac software that has Audio Unit support. Not sure if you want this in your repository, but thought I would submit it as a pullreq just in case.

Thank you for your amazing work on the emulator!