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/AudioUtils.java

@@ -0,0 +1,57 @@
+/*******************************************************************************
+ * sdrtrunk
+ * Copyright (C) 2014-2016 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;
+
+import io.github.dsheirer.sample.ConversionUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.List;
+
+public class AudioUtils
+{
+    private final static Logger mLog = LoggerFactory.getLogger(AudioUtils.class);
+
+    /**
+     * Converts the audio packets into a byte array of 16-bit, little-endian audio samples
+     */
+    public static byte[] convertTo16BitSamples(List<AudioPacket> audioPackets)
+    {
+        ByteArrayOutputStream stream = new ByteArrayOutputStream();
+
+        try
+        {
+            for(AudioPacket packet: audioPackets)
+            {
+                //Converting from 32-bit floats to signed 16-bit samples
+                ByteBuffer buffer = ConversionUtils.convertToSigned16BitSamples(packet.getAudioBuffer().getSamples());
+                stream.write(buffer.array());
+            }
+        }
+        catch(IOException e)
+        {
+            mLog.error("Error writing converted PCM bytes to output stream");
+        }
+
+        return stream.toByteArray();
+    }
+}