Capture UI basic controls.

Tuning, LNA/VGA gain, second IF and "channel" RSSI. Use ReceiverModel, so that audio receiver parameters come across for quicker capture configuration.

firmware/application/receiver_model.hpp

@@ -37,6 +37,7 @@ public:
 		NarrowbandFMAudio = 1,
 		WidebandFMAudio = 2,
 		SpectrumAnalysis = 4,
+		Capture = 7,
 	};
 
 	rf::Frequency tuning_frequency() const;