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/spectrum/SpectralDisplayAdjuster.java

@@ -1,35 +1,30 @@
 package spectrum;
 
+import dsp.filter.smoothing.SmoothingFilter.SmoothingType;
+
 public interface SpectralDisplayAdjuster
 {
-/**
+	/**
 	 * Gets the averaging value indicating the number of FFT results that are
 	 * averaged to produce each FFT results output.
 	 * 
 	 * @return averaging value ( 2 - 50 )
 	 */
 	public int getAveraging();
-	
-	/**
-	 * Sets the averaging value indicating the number of FFT results to average
-	 * when producing an FFT output result.
-	 * @param averaging value ( 2 - 50 )
-	 */
 	public void setAveraging( int averaging );
 
 	/**
-	 * Gets the dBm scale used when plotting the FFT bin results in the FFT
-	 * spectral display.  This value determines the smallest displayed power
-	 * spectrum value that is shown at the bottom of the display.
+	 * Sets the smoothing filter averaging window width.  
 	 * 
-	 * @return averaging value ( 1 - 50 )
+	 * Valid values are odd in the range 3 - 29
 	 */
-	public int getDBScale();
-	
+	public int getSmoothing();
+	public void setSmoothing( int smoothing );
+
 	/**
-	 * Sets the dBm scale from 0 (top of display) to the scale value (bottom).
-	 * 
-	 * @param baseline value ( -160 to -30 dBm )
+	 * Sets the type of smoothing filter to use.
 	 */
-	public void setDBScale( int baseline );
+	public SmoothingType getSmoothingType();
+	public void setSmoothingType( SmoothingType type );
+	
 }