#652 USB Tuner Error Handling Enhancements (#653)

-Separates USB timeout event processing to a dedicated thread
-Updates USB transfer buffer processor to better detect errors and auto-restart on error (max 3 times)
-Updates Tuner to add an error state and SourceManager to not select tuners with an error state
-Updates ChannelProcessingManager to auto-shutdown channels sourced from tuners set with error state
-Improves logging of USB related errors.

src/main/java/io/github/dsheirer/gui/SDRTrunk.java

@@ -1,7 +1,7 @@
 /*
  *
  *  * ******************************************************************************
- *  * Copyright (C) 2014-2019 Dennis Sheirer
+ *  * Copyright (C) 2014-2020 Dennis Sheirer
  *  *
  *  * This program is free software: you can redistribute it and/or modify
  *  * it under the terms of the GNU General Public License as published by
@@ -474,7 +474,6 @@ public class SDRTrunk implements Listener<TunerEvent>
         mAudioPacketManager.stop();
         mLog.info("Stopping spectral display ...");
         mSpectralPanel.clearTuner();
-        mLog.info("Releasing tuners ...");
         mSourceManager.shutdown();
         mLog.info("Shutdown complete.");
         mApplicationLog.stop();