Added Visualizer effect.

The visualizer enables application to retrieve part of the currently playing audio for visualization purpose.
It is not an audio recording interface and only returns partial and low quality audio content as a waveform or
a frequency representation (FFT).

Removed temporary hack made in MediaPlayer for animated wall papers based on audio visualization (snoop() method.

This commit also includes a change in AudioEffect class:
 - the enable()/disable() methods have been replaced bya more standard setEnabled() method.
 - some fixes in javadoc

Change-Id: Id092a1340e9e38dae68646ade7be054e3a36980e
22 files changed