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/audio/squelch/ISquelchStateListener.java

@@ -0,0 +1,8 @@
+package io.github.dsheirer.audio.squelch;
+
+import io.github.dsheirer.sample.Listener;
+
+public interface ISquelchStateListener
+{
+	public Listener<SquelchState> getSquelchStateListener();
+}

src/main/java/io/github/dsheirer/audio/squelch/ISquelchStateProvider.java

@@ -0,0 +1,9 @@
+package io.github.dsheirer.audio.squelch;
+
+import io.github.dsheirer.sample.Listener;
+
+public interface ISquelchStateProvider
+{
+	public void setSquelchStateListener( Listener<SquelchState> listener );
+	public void removeSquelchStateListener();
+}

src/main/java/io/github/dsheirer/audio/squelch/ManualSquelchController.java

@@ -0,0 +1,40 @@
+/*******************************************************************************
+ *     SDR Trunk 
+ *     Copyright (C) 2015 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
+ *     the Free Software Foundation, either version 3 of the License, or
+ *     (at your option) any later version.
+ * 
+ *     This program is distributed in the hope that it will be useful,
+ *     but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *     GNU General Public License for more details.
+ * 
+ *     You should have received a copy of the GNU General Public License
+ *     along with this program.  If not, see <http://www.gnu.org/licenses/>
+ ******************************************************************************/
+
+package io.github.dsheirer.audio.squelch;
+
+
+/**
+ * Provides squelch control based on presense of decoded audio samples.
+ * 
+ * NOTE: this class is not yet fully implemented with audio sample processing
+ * and currently only provides user driven squelch control
+ */
+public class ManualSquelchController extends SquelchController
+{
+	public ManualSquelchController()
+	{
+		mSquelchMode = SquelchMode.NONE;
+	}
+
+	@Override
+	public void setSquelchMode( SquelchMode mode )
+	{
+		//TODO: add functionality
+	}
+}

src/main/java/io/github/dsheirer/audio/squelch/SquelchController.java

@@ -0,0 +1,122 @@
+/*******************************************************************************
+ *     SDR Trunk 
+ *     Copyright (C) 2015 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
+ *     the Free Software Foundation, either version 3 of the License, or
+ *     (at your option) any later version.
+ * 
+ *     This program is distributed in the hope that it will be useful,
+ *     but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *     GNU General Public License for more details.
+ * 
+ *     You should have received a copy of the GNU General Public License
+ *     along with this program.  If not, see <http://www.gnu.org/licenses/>
+ ******************************************************************************/
+
+package io.github.dsheirer.audio.squelch;
+
+import io.github.dsheirer.sample.Broadcaster;
+import io.github.dsheirer.sample.Listener;
+import io.github.dsheirer.sample.real.RealBuffer;
+import io.github.dsheirer.sample.real.RealSampleListener;
+import io.github.dsheirer.sample.real.RealToRealBufferAssembler;
+
+/**
+ * Squelch control - receives single audio samples or real audio buffers and
+ * adjusts squelch state either based on the audio samples or based on external
+ * control inputs.  
+ * 
+ * Assembles received single audio samples into real sample buffers for
+ * consumption by an external audio processor, like the AudioPacketProcessor
+ * class.
+ */
+public abstract class SquelchController 
+				implements Listener<RealBuffer>, RealSampleListener
+{
+	private Broadcaster<SquelchState> mSquelchStateBroadcaster = new Broadcaster<>();
+	private Listener<RealBuffer> mAudioListener;
+	protected SquelchState mSquelchState = SquelchState.UNSQUELCH;
+	protected SquelchMode mSquelchMode = SquelchMode.MANUAL;
+	
+	private RealToRealBufferAssembler mSampleAssembler = new RealToRealBufferAssembler( 512 );
+	
+	public SquelchController()
+	{
+		mSampleAssembler.setListener( this );
+	}
+	
+	@Override
+	public void receive( float sample )
+	{
+		mSampleAssembler.receive( sample );
+	}
+
+	@Override
+	public void receive( RealBuffer buffer )
+	{
+		if( mAudioListener != null )
+		{
+			mAudioListener.receive( buffer );
+		}
+	}
+
+	public abstract void setSquelchMode( SquelchMode mode );
+
+	public SquelchMode getSquelchMode()
+	{
+		return mSquelchMode;
+	}
+
+	public void setSquelchState( SquelchState state )
+	{
+		mSquelchState = state;
+	}
+
+	public SquelchState getSquelchState()
+	{
+		return mSquelchState;
+	}
+
+	public boolean isSquelched()
+	{
+		switch( mSquelchMode )
+		{
+			case AUTOMATIC:
+			case MANUAL:
+				return mSquelchState == SquelchState.SQUELCH;
+			case NONE:
+				return false;
+			default:
+				return false;
+		}
+	}
+	
+	public void addSquelchStateListener( Listener<SquelchState> listener )
+	{
+		if( listener != null )
+		{
+			mSquelchStateBroadcaster.addListener( listener );
+			
+			/* Send current squelch state to the listener */
+			listener.receive( mSquelchState );
+		}
+	}
+
+	public void removeSquelchStateListener( Listener<SquelchState> listener )
+	{
+		mSquelchStateBroadcaster.removeListener( listener );
+	}
+	
+	public void setAudioListener( Listener<RealBuffer> listener )
+	{
+		mAudioListener = listener;
+	}
+	
+	public void removeAudioListener( Listener<RealBuffer> listener )
+	{
+		mAudioListener = null;
+	}
+}

src/main/java/io/github/dsheirer/audio/squelch/SquelchMode.java

@@ -0,0 +1,25 @@
+package io.github.dsheirer.audio.squelch;
+
+/**
+ * Squelch state for a decoding channel.  The state determines the handling of
+ * any audio packets processed by the channel state.
+ */
+public enum SquelchMode
+{
+	/**
+	 * Automatic: decoded message activity dictates squelch state and determines
+	 * if audio is passed
+	 */
+	AUTOMATIC,
+	
+	/**
+	 * Manually applied squelch noise level threshold determines if audio is
+	 * passed.
+	 */
+	MANUAL,
+	
+	/**
+	 * No Squelch - no squelch is applied and all audio is passed
+	 */
+	NONE;
+}

src/main/java/io/github/dsheirer/audio/squelch/SquelchState.java

@@ -0,0 +1,7 @@
+package io.github.dsheirer.audio.squelch;
+
+public enum SquelchState
+{
+	SQUELCH,
+	UNSQUELCH;
+}

src/main/java/io/github/dsheirer/audio/squelch/TrunkingSquelchController.java

@@ -0,0 +1,55 @@
+/*******************************************************************************
+ *     SDR Trunk 
+ *     Copyright (C) 2015 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
+ *     the Free Software Foundation, either version 3 of the License, or
+ *     (at your option) any later version.
+ * 
+ *     This program is distributed in the hope that it will be useful,
+ *     but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *     GNU General Public License for more details.
+ * 
+ *     You should have received a copy of the GNU General Public License
+ *     along with this program.  If not, see <http://www.gnu.org/licenses/>
+ ******************************************************************************/
+
+package io.github.dsheirer.audio.squelch;
+
+public class TrunkingSquelchController extends SquelchController
+{
+	private boolean mAllowSquelchOverride = true;
+	
+	public TrunkingSquelchController()
+	{
+	}
+	
+	/**
+	 * Provides control over audio stream as directed by an external trunking
+	 * channel state.
+	 * 
+	 * Override automatic squelch control by setting the squelch mode to none.
+	 * 
+	 * Disable automatic control override by setting allowManualOverride to false;
+	 * 
+	 * Note: this control does not respond to squelch mode manual.
+	 */
+	public TrunkingSquelchController( boolean allowSquelchOverride )
+	{
+		mAllowSquelchOverride = allowSquelchOverride;
+		
+		mSquelchMode = SquelchMode.AUTOMATIC;
+	}
+
+	@Override
+	public void setSquelchMode( SquelchMode mode )
+	{
+		if( mode == SquelchMode.AUTOMATIC ||
+			( mode == SquelchMode.NONE && mAllowSquelchOverride ) )
+		{
+			mSquelchMode = mode;
+		}
+	}
+}