Modifications in audio effect engine state management.

- Separate the updating of effect engine state from the process call in EffectModule so that the state
of all effects in the same effect chain is updated simultaneusly before all process functions are called.
- Added a mechanism for the effect engine to continue being called for processing after receiving the disable
commands untils it considers that the framework can stop calling the process function without causing
a glitch or loosing some effect tail.
- Updated test reverb and equalizer to support this new feature

Change-Id: Icb56ae2c84c076d4dbad6cf733b1a62f823febe7