Volume control setting

[[Unknown]]

The problem with these settings is that they are technically labeled wrong.

BGM = Atrac, MP3
SFX = SAS (VAG, PCM, etc.)

Generally speaking, this is often right. However, in several games it's wrong:

* It's possible to output audio directly (to the audio backend), and we have no idea if it's BGM of SFX or what.
* Sound effects (and especially voices) are sometimes Atrac, but we count these as BGM.
* Music is sometimes fed through SAS (e.g. when it is VAG or PCM.)

If we keep them, I would change their names to be more correct, but they will probably make less sense to the average user...

-[Unknown]