Idle time = 58 minutes not 1 hour.

I forgot to save before I commited earlier!
Issue 490


git-svn-id: http://svn.dmdirc.com/trunk@4092 00569f92-eb28-0410-84fd-f71c24880f

src/com/dmdirc/addons/logging/LoggingPlugin.java

 	 */
 	private void timerTask() {
 		// Oldest time to allow
-		final long oldestTime = System.currentTimeMillis() - 3600000;
+		final long oldestTime = System.currentTimeMillis() - 3480000;
 		
 		synchronized (openFiles) {
 			for (String filename : (new Hashtable<String, OpenFile>(openFiles)).keySet()) {