lib/metro/scene.rb
def add_actors_to_scene
      self.class.actors.each do |scene_actor|
        actor_instance = scene_actor.create
        actor_instance.scene = self
        send "#{scene_actor.name}=", actor_instance
      end
    end
def add_actors_to_scene
      self.class.actors.each do |scene_actor|
        actor_instance = scene_actor.create
        actor_instance.scene = self
        send "#{scene_actor.name}=", actor_instance
      end
    end
Setups up the Actors for the Scene based on the ModelFactories that have been
 defined.

 @note this method should not be overriden, otherwise the actors will perish!
 @see #after_initialize