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/module/ProcessingChain.java

@@ -27,7 +27,6 @@ import java.util.concurrent.atomic.AtomicBoolean;
 import message.IMessageListener;
 import message.IMessageProvider;
 import message.Message;
-import module.decode.Decoder;
 import module.decode.event.CallEvent;
 import module.decode.event.ICallEventListener;
 import module.decode.event.ICallEventProvider;
@@ -42,6 +41,7 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import sample.Broadcaster;
+import sample.Buffer;
 import sample.Listener;
 import sample.complex.ComplexBuffer;
 import sample.complex.IComplexBufferListener;

src/module/decode/ltrnet/LTRCallEvent.java

@@ -19,7 +19,6 @@ package module.decode.ltrnet;
 
 import module.decode.DecoderType;
 import module.decode.event.CallEvent;
-import module.decode.ltrstandard.LTRStandardMessage;
 import alias.Alias;
 import alias.AliasList;
 

src/module/decode/mpt1327/MPT1327Decoder.java

@@ -40,7 +40,6 @@ import sample.real.RealBuffer;
 import alias.AliasList;
 import bits.MessageFramer;
 import bits.SyncPattern;
-import controller.channel.Channel.ChannelType;
 import dsp.filter.FilterFactory;
 import dsp.filter.Filters;
 import dsp.filter.Window.WindowType;

src/module/decode/p25/P25DecoderPanel.java

@@ -21,7 +21,6 @@ import java.awt.EventQueue;
 
 import javax.swing.JLabel;
 
-import module.decode.p25.P25Decoder.Modulation;
 import module.decode.state.ChangedAttribute;
 import module.decode.state.DecoderPanel;
 import net.miginfocom.swing.MigLayout;

src/module/decode/p25/P25_LSMDecoder.java

@@ -36,7 +36,6 @@ import sample.complex.ComplexBufferToStreamConverter;
 import sample.complex.IComplexBufferListener;
 import source.tuner.frequency.FrequencyCorrectionControl;
 import alias.AliasList;
-import controller.channel.Channel.ChannelType;
 import dsp.filter.FilterFactory;
 import dsp.filter.Window.WindowType;
 import dsp.filter.fir.complex.ComplexFIRFilter_CB_CB;

src/module/decode/p25/audio/P25AudioModule.java

@@ -135,7 +135,7 @@ public class P25AudioModule extends Module implements Listener<Message>,
 			library = (AudioConversionLibrary)temp.newInstance();
 			
 			if( ( library.getMajorVersion() == 0 && library.getMinorVersion() >= 3 ) ||
-				  library.getMajorVersion() > 0 )
+				  library.getMajorVersion() >= 1 )
 			{
 				mAudioConverter = library.getAudioConverter( IMBE_CODEC, 
 						AudioFormats.PCM_SIGNED_48KHZ_16BITS_MONO );

src/module/decode/state/ChannelList.java

@@ -30,10 +30,11 @@ import javax.swing.JPopupMenu;
 import javax.swing.JSeparator;
 import javax.swing.SwingUtilities;
 
+import net.miginfocom.swing.MigLayout;
+
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import net.miginfocom.swing.MigLayout;
 import playlist.PlaylistManager;
 import settings.ColorSetting.ColorSettingName;
 import settings.ColorSettingMenuItem;

src/module/decode/state/ChannelStatePanel.java

@@ -7,20 +7,14 @@ import java.awt.GradientPaint;
 import java.awt.Graphics;
 import java.awt.Graphics2D;
 import java.awt.Paint;
-import java.awt.event.ActionEvent;
-import java.awt.event.ActionListener;
 import java.util.ArrayList;
 import java.util.List;
 
 import javax.swing.JLabel;
 import javax.swing.JMenu;
-import javax.swing.JMenuItem;
 import javax.swing.JPanel;
-import javax.swing.JSeparator;
 
-import module.decode.Decoder;
 import module.decode.DecoderFactory;
-import module.decode.event.ActivitySummaryFrame;
 import net.miginfocom.swing.MigLayout;
 
 import org.slf4j.Logger;

src/module/demodulate/fm/FMDemodulatorModule.java

@@ -33,7 +33,6 @@ import source.tuner.frequency.FrequencyCorrectionControl;
 import source.tuner.frequency.IFrequencyCorrectionController;
 import dsp.filter.FilterFactory;
 import dsp.filter.Window.WindowType;
-import dsp.filter.dc.AveragingDCRemovalFilter_RB;
 import dsp.filter.dc.DCRemovalFilter_RB;
 import dsp.filter.fir.complex.ComplexFIRFilter_CB_CB;
 import dsp.fm.FMDemodulator_CB;
@@ -102,7 +101,7 @@ public class FMDemodulatorModule extends Module implements IComplexBufferListene
 		
 		if( mRemoveDC )
 		{
-			mDCRemovalFilter = new AveragingDCRemovalFilter_RB( DC_REMOVAL_RATIO );
+			mDCRemovalFilter = new DCRemovalFilter_RB( DC_REMOVAL_RATIO );
 			mUnfilteredBufferBroadcaster.addListener( mDCRemovalFilter );
 		}
 	}

src/module/log/EventLogManager.java

@@ -21,13 +21,13 @@ import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.List;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-import controller.channel.Channel;
 import module.Module;
 import module.log.MessageEventLogger.Type;
 import module.log.config.EventLogConfiguration;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import properties.SystemProperties;
 
 public class EventLogManager