* helper to read the last few lines of a textfile

* use that to render the last few lines of the wrapper log on /logs.jsp (for the on demand stack trace)
* thread creation / finalization logging
* support a hard restart (stop immediately and restart the JVM) - useful for rerunning clients.config (etc)
* systray when not supported

router/java/src/net/i2p/router/Router.java

@@ -539,6 +539,7 @@ public class Router {
     public static final int EXIT_GRACEFUL = 2;
     public static final int EXIT_HARD = 3;
     public static final int EXIT_OOM = 10;
+    public static final int EXIT_HARD_RESTART = 4;
     
     public void shutdown(int exitCode) {
         _isAlive = false;