Decouples DecoderState from the Decoder and makes DecoderState inherit

from Module so that Decoder can function independent of DecoderSTate and
DecoderState can more cleanly interface with other modules. 

Resolves issue with LTR-type decoders where the AudioModule was
filtering demodulated audio buffers before the decoder received the
audio - demodulated audio buffers are now copied before creating
AudioPackets.

src/module/decode/state/TrafficChannelManager.java

@@ -315,13 +315,13 @@ public class TrafficChannelManager extends Module
 	}
 
 	@Override
-	public void setCallEventListener( Listener<CallEvent> listener )
+	public void addCallEventListener( Listener<CallEvent> listener )
 	{
 		mCallEventListener = listener;
 	}
 
 	@Override
-	public void removeCallEventListener()
+	public void removeCallEventListener( Listener<CallEvent> listener )
 	{
 		mCallEventListener = null;
 	}