OSX Mavericks Support

This pull request closes #509

I'd also like to publish this to the main page if we're in agreement: 
https://github.com/tresf/lmms/wiki/Compiling-lmms-OSX

There's still much to be worked out on this platform.  I would like to start opening up individual bug reports to address each bug individually.  The build instructions in combination with these commits should make community OSX bug fixing feasible.

-Tres