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/audio/AudioModule.java

@@ -1,5 +1,7 @@
 package audio;
 
+import java.util.Arrays;
+
 import module.Module;
 
 import org.slf4j.Logger;
@@ -115,7 +117,9 @@ public class AudioModule extends Module implements IAudioPacketProvider,
 	{
 		if( mAudioPacketListener != null && mSquelchState == SquelchState.UNSQUELCH )
 		{
-			float[] audio = buffer.getSamples();
+			/* We make a copy of the samples, so that we don't affect any other
+			 * processes that might be concurrently processing the same buffer */
+			float[] audio = Arrays.copyOf( buffer.getSamples(), buffer.getSamples().length );
 			
 			mAudioFilter.filter( audio );