Add a unregisteredEvent method to clean registeredEvent, to allow gabage collection of waveform instance
Add a unregisteredEvent method to clean registeredEvent, to allow gabage collection of waveform instance

agamemnus/wavesurfer.js,katspaugh/wavesurfer.js,ffxsam/wavesurfer.js,katspaugh/wavesurfer.js,agamemnus/wavesurfer.js,ale-grosselle/wavesurfer.js,ffxsam/wavesurfer.js,ale-grosselle/wavesurfer.js