In some complex ALSA setups, using PCM or Master is not the right thing
to do, so allow a custom mixer element name to be specified in the config
file for this use case.
Request and initial patch by Kurt Vanderlinden <kurt.vanderlinden@skynet.be>.
It is now clear that multi-library support will not happen, so remove whatever
provisions were in the code for that.
It comes with a small change to the configuration file, too.
With this, DB schema version went to 9.
