Feature: Datapixx audio

[dekuenstle]

The Viewpixx/Datapixx can be used to play sounds, too. It would be great to create a psychopy sound backend that uses pypixxlib's audio functions. Ultimately, the backend should provide a sound class (i.e. play, stop, ...) and a getDevices function.
This backend should replace the default before the experiment starts (like here)

Here is a minimal example of how to play sound with pypixxlib.