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/module/log/EventLogger.java

@@ -0,0 +1,139 @@
+/*******************************************************************************
+ * 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.module.log;
+
+import io.github.dsheirer.module.Module;
+import io.github.dsheirer.util.TimeStamp;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.OutputStreamWriter;
+import java.io.Writer;
+import java.nio.file.Path;
+import java.util.concurrent.ScheduledExecutorService;
+
+public abstract class EventLogger extends Module
+{
+    private final static Logger mLog = LoggerFactory.getLogger(EventLogger.class);
+
+    private static final String[] ILLEGAL_FILENAME_CHARACTERS = {"#", "%", "&", "{", "}", "\\", "<", ">",
+        "*", "?", "/", " ", "$", "!", "'", "\"", ":", "@", "+", "`", "|", "="};
+
+    private Path mLogDirectory;
+    private String mFileNameSuffix;
+    private String mLogFileName;
+    protected Writer mLogFile;
+
+    public EventLogger(Path logDirectory, String fileNameSuffix)
+    {
+        mLogDirectory = logDirectory;
+        mFileNameSuffix = fileNameSuffix;
+    }
+
+    public String toString()
+    {
+        if(mLogFileName != null)
+        {
+            return mLogFileName;
+        }
+        else
+        {
+            return "Unknown";
+        }
+    }
+
+    public abstract String getHeader();
+
+    @Override
+    public void start(ScheduledExecutorService executor)
+    {
+        if(mLogFile == null)
+        {
+            try
+            {
+                StringBuilder sb = new StringBuilder();
+                sb.append(mLogDirectory);
+                sb.append(File.separator);
+                sb.append(TimeStamp.getTimeStamp("_"));
+                sb.append("_");
+                sb.append(replaceIllegalCharacters(mFileNameSuffix));
+
+                mLogFileName = sb.toString();
+
+                mLogFile = new OutputStreamWriter(new FileOutputStream(mLogFileName));
+
+                write(getHeader());
+            }
+            catch(FileNotFoundException e)
+            {
+                mLog.error("Couldn't create log file in directory:" + mLogDirectory);
+            }
+        }
+    }
+
+    /**
+     * Replaces any illegal filename characters in the proposed filename
+     */
+    private String replaceIllegalCharacters(String filename)
+    {
+        for(String illegalCharacter : ILLEGAL_FILENAME_CHARACTERS)
+        {
+            filename = filename.replace(illegalCharacter, "_");
+        }
+
+        return filename;
+    }
+
+    public void stop()
+    {
+        if(mLogFile != null)
+        {
+            try
+            {
+                mLogFile.flush();
+                mLogFile.close();
+                mLogFile = null;
+            }
+            catch(Exception e)
+            {
+                mLog.error("Couldn't close log file:" + mFileNameSuffix);
+            }
+        }
+    }
+
+    protected void write(String eventLogEntry)
+    {
+        if(mLogFile != null)
+        {
+            try
+            {
+                mLogFile.write(eventLogEntry + "\n");
+                mLogFile.flush();
+            }
+            catch(IOException e)
+            {
+                mLog.error("Error writing entry to event log file", e);
+            }
+        }
+    }
+}