fix(Rankboard.java): ajout arraylist clone

src/Game.java

@@ -243,14 +243,17 @@ public class Game
      *
      * @throws InterruptedException si le thread est interrompu pendant wait()
      */
-    private synchronized void step() throws InterruptedException
+    private void step() throws InterruptedException
     {
-        for (int i = 0; i < cars.size(); i++)
+        for (Car car : cars)
         {
-            while (isPaused)
-                wait();
+			synchronized(this)
+			{
+				while (isPaused)
+					wait();
+			}
 
-            cars.get(i).run();
+            car.run();
 
             for (GObserver o : obs)
             {