Make musicpd startup somewhat system agnostic

I know that this approach is rather crappy. But only two platforms
are not enough to justify the trouble with a seperate script.
Refactor the volum controls into a small script
Refactor .xinitrc
Replace comix with mcomix
Increase Linux compatibility
With Xorg 1.16 -retros is gone for good. At least as alias.
Rework key bindings
Bigger monitors :)
Customized menu