MIDI mapping for Denon MC6000MK2

Finally ready for testing by a wider audience. All the basic functionality should be implemented, filters are available and also an initial mapping for the effect units FX1/FX2. Updates will follow from time to time ;) 

Unfortunately no feedback from other users, yet. I'm already using the controller with this mapping myself.

See also: http://www.mixxx.org/forums/viewtopic.php?f=7&t=6251