Updates pull request from Roman Tsypuk to convert the build system from

ant to gradle.  Removes linux and windows application launch scripts and
produces an executable jar with all resources included.

src/main/java/io/github/dsheirer/spectrum/converter/DFTResultsConverter.java

@@ -0,0 +1,46 @@
+package io.github.dsheirer.spectrum.converter;
+
+import io.github.dsheirer.spectrum.DFTResultsListener;
+import io.github.dsheirer.spectrum.DFTResultsProvider;
+
+import java.util.concurrent.CopyOnWriteArrayList;
+
+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 );
+		}
+	}
+}