Add audio support

Needed for bone drilling simulation

Some options:

http://www.openal-soft.org/ (LGPL)
http://audiere.sourceforge.net/home.php (LGPL)
https://www.sfml-dev.org/index.php (zlib license)
http://www.portaudio.com/ (GNU)
https://github.com/google/pindrop (Apache License v2.0)
https://www.libsdl.org/ (zlib license) [Nick: we can possibly separate out the audio from SDL. I think VTK uses SDL for VR, but AFAIK it uses GLUT for non-VR]

Edited Jul 29, 2017 by Sreekanth Arikatla