initial pause resume, resume time is off
working pause / resume
Closes #8
fix recently broken getLength() in file player
prime file player before playing
Closes #5
expose prime() as a public function for file player
handle case where play() / pause() calls are unbalanced
add playAtSampleTime() to ofxAudioUnitFilePlayer
(allows playback starting at an arbitrary point in the file)
make stop() reset the pause playhead in file player
Merge pull request #10 from admsyn/fileplayer-pause-resume

ofxAudioUnitFilePlayer pause / resume, priming, seeking