Added println

src/main/java/it/unibo/bombardero/core/BombarderoEngine.java

@@ -51,7 +51,7 @@ private void waitForNextFrame(final long currentCycleStartTime) {
             try {
                 Thread.sleep(BombarderoEngine.SLEEP_TIME - currentCycleElapsedTime);
             } catch (IllegalArgumentException | InterruptedException e) {
-                e.printStackTrace();
+                System.out.println("Exception in thread sleeping: " + e.getMessage());
             }
         }
     }