lib/metro/scenes.rb
def apply_post_filters(new_scene,options)
      post_filters.inject(new_scene) {|scene,post| post.filter(scene,options) }
    end
def apply_post_filters(new_scene,options)
      post_filters.inject(new_scene) {|scene,post| post.filter(scene,options) }
    end
Apply all the post filtering to the specified scene with the given options

 @return a Scene object that has been filtered.