Add independant switches for enabling upmixing and downmixing

[Cimi]

I would like to downmix channels, but I don't want upmix. I would like to disable upmixing through the deamon.conf file.

More precisely, I would like to have the front-center channel reproduced by the two front speakers, and the LFE reproduced by every speaker (or the front ones). When playing a stereo track, I would like to listen that track only on the front speakers.

[The only way I would like to have upmixing is when I'm seeing a stereo movie, and I would like to add a surround effect like mplayer does (by adding a 15ms delay and upmixing a bit the stereo channels to the rear speakers). Unfortunately this feature can't coexist with the non-upmix config unless you can enable it per-application just when reproducing a movie.]