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/util/MemoryUsageLogger.java

@@ -0,0 +1,54 @@
+/*******************************************************************************
+ * sdrtrunk
+ * Copyright (C) 2014-2017 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.util;
+
+import ch.qos.logback.classic.pattern.ClassicConverter;
+import ch.qos.logback.classic.spi.ILoggingEvent;
+import org.apache.commons.io.FileUtils;
+
+/**
+ * Custom logging plugin for logging memory usage with logback
+ *
+ * Add the following to the logback.xml configuration file to use this custom converter:
+ *
+ * <conversionRule conversionWord="memory_usage" converterClass="MemoryUsageLogger" />
+ *
+ * Update the encoder pattern to include %memory_usage within the pattern
+ */
+public class MemoryUsageLogger extends ClassicConverter
+{
+    @Override
+    public String convert(ILoggingEvent iLoggingEvent)
+    {
+        //Method argument is ignored - we simply return memory usage statistics
+        long allocated = Runtime.getRuntime().totalMemory();
+        long free = Runtime.getRuntime().freeMemory();
+        long used = allocated - free;
+
+        int usedPercentage = (int)((double)(used) / (double)allocated * 100.0);
+
+        StringBuilder sb = new StringBuilder();
+
+        sb.append("[").append(FileUtils.byteCountToDisplaySize(used).replace(" ", ""));
+        sb.append("/").append(FileUtils.byteCountToDisplaySize(allocated).replace(" ", ""));
+        sb.append(" ").append(usedPercentage).append("%]");
+
+        return sb.toString();
+    }
+}