added possiblity to build jar file and override shutdown behavior when closing via alt-f4 or the close button of the window

Projekte/mdga/client/src/main/java/pp/mdga/client/MdgaApp.java

@@ -88,7 +88,7 @@ public class MdgaApp extends SimpleApplication {
     private final TimerManager timerManager = new TimerManager();
 
 
-    public static final int DEBUG_MULTIPLIER = 0;
+    public static final int DEBUG_MULTIPLIER = 1;
 
     /**
      * Constructs a new MdgaApp instance.
@@ -403,5 +403,14 @@ public TimerManager getTimerManager() {
     public CeremonyView getCeremonyView() {
         return ceremonyView;
     }
+
+    @Override
+    public void destroy() {
+        afterGameCleanup();
+        if (executor != null) {
+            executor.shutdown();
+        }
+        super.destroy();
+    }
 }