replaygain pre-amp configuration support
Yet another ReplayGain commit :-/
I'm going back to mp.setVolume(). The Android Equalizer turned out to be too buggy.
The only advantage of using it would be the possibilty to go > 100%, but this feature just
doesn't work well - even on a Nexus 7 running Stock 4.2.2.
So there is no need to use the EQ if we are still limited to 100%