[1/3] Effects: Add a stereo widening effect

Based on self knowledge.
Aside from the filter, a HighPass method has been
added to Biquad in the DSP library

Change-Id: I5dc8afa75cdf179c71ec38359887be9a5a60d4bd

Conflicts:
	src/com/bel/android/dspmanager/service/HeadsetService.java