migrate to AVFoundation API for Audio Sessions
handle audio interruptions in ofxiOSSoundPlayer
properly set the audio category on iOS 5
add feature allowing iOS sound to mix with other apps
closes #878
remove stray call to C AudioSession API
Merge pull request #2187 from admsyn/ios-sound-futureproof

AVFoundation API for iOS Audio Sessions
Merge branch 'develop' of git://github.com/openframeworks/openFrameworks into featue_programmableGLTextureMipmaps