* Initial work on add support for rotating control channels.
* Creates multiple frequency editor control.
* Updates channel source editor to allow user to select multi-frequency
configuration and add multiple frequencies.
* Adds full support for rotating control channels to the P25 channelizer.
Users define multiple frequencies in the channel source configuration.
The decoder monitors the state of the channel for a CONTROL state. If
the state does not stay in the CONTROL state for a user-specified delay
value, then the decoder rotates to the next frequency in the list. This
behavior continues until the decoder state once again changes to CONTROL.
This is NOT a 'scanner' feature.
