ofSoundBuffer and ofSoundObject

A number of cross-platform changes introducing an ofSoundObject and ofSoundBuffer. By @admsyn @bakercp @mazbox

ofSoundBuffer allows users to load sounds from disk and manipulate them on a sample-by-sample basis.

Classes inheriting ofSoundObject allow you to create filter chains.

This code is incredibly well documented, and I recommend we merge it soon :) I'm so psyched to have this, I'm creating the PR on behalf of @admsyn ;)