public void AddEntity(DrawableEntity entity)
 {
     entity.OwnerScreen = this;
     entity.LoadContent();
     entities.Add(entity);
     if (entity is PlayerEntity)
         player = (PlayerEntity)entity;
 }
 public void RemoveEntity(DrawableEntity entity)
 {
     entity.UnloadContent();
     entities.Remove(entity);
     entitiesToUpdate.Remove(entity);
 }