Fix serialisation issue

Projekte/mdga/client/src/main/java/pp/mdga/client/server/MdgaServer.java

@@ -2,6 +2,7 @@
 
 import com.jme3.network.*;
 import com.jme3.network.serializing.Serializer;
+import com.jme3.network.serializing.serializers.EnumSerializer;
 import pp.mdga.Resources;
 import pp.mdga.game.*;
 import pp.mdga.message.client.*;
@@ -145,6 +146,10 @@ private void initializeSerializables() {
         Serializer.registerClass(StartNode.class);
         Serializer.registerClass(PlayerData.class);
         Serializer.registerClass(HomeNode.class);
+
+        Serializer.registerClass(Color.class, new EnumSerializer());
+        Serializer.registerClass(PieceState.class, new EnumSerializer());
+        Serializer.registerClass(ShieldState.class, new EnumSerializer());
     }
 
     private void registerListeners() {

Projekte/mdga/model/src/main/java/pp/mdga/game/Color.java

@@ -1,9 +1,12 @@
 package pp.mdga.game;
 
+import com.jme3.network.serializing.Serializable;
+
 /**
  * This enumeration will be used to show the four different TSK which can be picked from a player.
  * In Addition, the NONE color will be used to show a none color.
  */
+@Serializable
 public enum Color {
     /**
      * Represents the air force color.

Projekte/mdga/model/src/main/java/pp/mdga/game/Node.java

@@ -10,7 +10,7 @@ public class Node {
     protected Piece occupant;
 
     public Node(){
-
+        occupant = new Piece(Color.AIRFORCE, PieceState.WAITING);
     }
 
     /**

Projekte/mdga/model/src/main/java/pp/mdga/game/PieceState.java

@@ -1,8 +1,11 @@
 package pp.mdga.game;
 
+import com.jme3.network.serializing.Serializable;
+
 /**
  * Represents the state of a piece.
  */
+@Serializable
 public enum PieceState {
     /**
      * The piece is active.