EN50494: add support for UniCable-Switches

EN50494 (better known as UniCable) is special kind of switch, that is able to connect up to 8 recievers on one single cable.
Most times the switch is build-in an LNB, but also switches with 2 connected universal-LNB exists.

The reciever send spezial DiESqC commands to the switch, and the switch tuned LNB the needed channel. 
The switch modulate the channel frequency to user-band frequency reserved for this reciever. The reciever can now recieve the channel on this user-band-frequency.