static public void RemoveMarkedEntities()
 {
     foreach (var Entity in EntityList)
     {
         if (Entity.marked_for_deletion)
         {
             var collisionComponent = Entity.GetComponent <CollisionComponent>();
             if (collisionComponent != null)
             {
                 CollisionManager.RemoveBody(collisionComponent.body);
             }
             CollisionManager.RemoveCollisionComponent(Entity);
             Entity.DeleteAllComponent();
         }
     }
     EntityList.RemoveAll((entity) => { return(entity.marked_for_deletion == true); });
 }