Correct the saving of the audio data

[stefanofossati]

Now we cannot set the audio from the mixer because the player.pref overwrite the value.

• Redesign the implementation of the audio setting of the player;
• Create more specific channels in order to be more flexible on the equalization
• audio track when the mode change is missing

[bottolo]

What would you suggest? Do we have to get rid of player prefs? I still think they could be useful to us!

Another thing is: do we really need that many channels? I've deleted some unused channels because there were too many.