Adds airspy USB tuner support and updates the spectral display

component.

-Airspy supported with 10 and 2.5 MSps sample rates.  Additional
decimation may be added later.

-Spectral display updated to include smoothing and filtering options.

Note: the decimated output of a tuner channel from the airspy is
48,076.9 samples per second, versus the normal 48 kHz decimated rate.
This is 1.0015 times the normal rate and doesn't appear to impact the
decoders or audio processing.  Therefore, no fractional resampling has
been added.

src/source/tuner/TunerManager.java

@@ -1,6 +1,6 @@
 /*******************************************************************************
  *     SDR Trunk 
- *     Copyright (C) 2014 Dennis Sheirer
+ *     Copyright (C) 2014,2015 Dennis Sheirer
  * 
  *     This program is free software: you can redistribute it and/or modify
  *     it under the terms of the GNU General Public License as published by
@@ -35,6 +35,8 @@ import source.SourceException;
 import source.config.SourceConfigTuner;
 import source.config.SourceConfiguration;
 import source.mixer.MixerManager;
+import source.tuner.airspy.AirspyTuner;
+import source.tuner.airspy.AirspyTunerController;
 import source.tuner.fcd.FCDTuner;
 import source.tuner.fcd.proV1.FCD1TunerController;
 import source.tuner.fcd.proplusV2.FCD2TunerController;
@@ -208,6 +210,8 @@ public class TunerManager
 			
 			switch( tunerClass )
 			{
+				case AIRSPY:
+					return initAirspyTuner( device, descriptor );
 				case ETTUS_USRP_B100:
 					return initEttusB100Tuner( device, descriptor );
 				case FUNCUBE_DONGLE_PRO:
@@ -250,6 +254,38 @@ public class TunerManager
 		
 		return new TunerInitStatus( null, "Unknown Device" );
 	}
+
+	private TunerInitStatus initAirspyTuner( Device device, 
+											 DeviceDescriptor descriptor )
+	{
+		try
+		{
+			AirspyTunerController airspyController = 
+				new AirspyTunerController( device, mResourceManager.getThreadPoolManager() );
+			
+			airspyController.init();
+			
+			AirspyTuner tuner = new AirspyTuner( airspyController );
+			
+			TunerConfiguration config = getTunerConfiguration( tuner );
+			
+			if( config != null )
+			{
+				tuner.apply( config );
+			}				
+			
+			return new TunerInitStatus( tuner, "LOADED" );
+		}
+		catch( SourceException se )
+		{
+			mLog.error( "couldn't construct Airspy controller/tuner", se );
+			
+			return new TunerInitStatus( null, 
+						"error constructing Airspy tuner controller" );
+		}
+	}
+
+
 	
 	private TunerInitStatus initEttusB100Tuner( Device device, 
 												DeviceDescriptor descriptor )