add drawable interface

core/src/netwerkprog/game/client/Map.java

@@ -0,0 +1,4 @@
+package netwerkprog.game.client;
+
+public class Map {
+}

core/src/netwerkprog/game/util/Drawable.java

@@ -0,0 +1,5 @@
+package netwerkprog.game.util;
+
+public interface Drawable extends Updatable {
+    void render();
+}