Channel Spectral Display

- Adds Channel Spectrum tab to display FFT of the audio output of the currently selected channel
 - Upgrades to JTransforms 3.0 FFT library
 - Adds three new context menus to main and channel spectral displays:
   -- Baseline - affects the vertical rendering baseline of the FFT
   -- Amplification - affects the vertical height of each FFT bin
   -- Averaging - affects how many FFTs are averaged to produce the display

src/spectrum/converter/DFTResultsConverter.java

@@ -0,0 +1,46 @@
+package spectrum.converter;
+
+import java.util.concurrent.CopyOnWriteArrayList;
+
+import spectrum.DFTResultsListener;
+import spectrum.DFTResultsProvider;
+
+public abstract class DFTResultsConverter 
+			implements DFTResultsListener, DFTResultsProvider
+{
+	private CopyOnWriteArrayList<DFTResultsListener> mListeners = 
+						new CopyOnWriteArrayList<DFTResultsListener>();
+	
+	/**
+	 * DFT Results Converter - for converting the output of the JTransforms
+	 * FFT library real and complex forward results
+	 */
+	public DFTResultsConverter()
+	{
+	}
+	
+	public void dispose()
+	{
+		mListeners.clear();
+	}
+
+	@Override
+    public void addListener( DFTResultsListener listener )
+    {
+		mListeners.add( listener );
+    }
+
+	@Override
+    public void removeListener( DFTResultsListener listener )
+    {
+		mListeners.remove( listener );
+    }
+
+	protected void dispatch( float[] results )
+	{
+		for( DFTResultsListener listener: mListeners )
+		{
+			listener.receive( results );
+		}
+	}
+}