Disable AppNap in QtCollider, sclang, and scsynth

This PR should disable appnap for supercollider processes (in paritcular: QtCollider, sclang & scsynth) on OS X 10.9. It will also inform OS X that we require high-quality-and-frequency timers.

- Should still compile against earlier OS X SDKs (tested against 10.8)
- Uses runtime API detection, so it will still disable appnap on 10.9, even if you compile against 10.8

To compile, you'll need to apply #994 first: https://github.com/supercollider/supercollider/pull/994