def render(svg, options = {})
      #TODO ensure this works with new points
      #current_points = points
      layers.each_with_index do |layer,i|
        
        #real_points = layer.points
        #layer.points = current_points
        layer_options = options.dup
 
        layer_options[:num_bars] = layers.size
        layer_options[:position] = i
        layer_options[:color] = layer.preferred_color || layer.color || options[:theme].next_color
        layer.render(svg, layer_options)
              
        options.merge(layer_options)
        
        #layer.points = real_points
        #layer.points.each_with_index { |val, idx| current_points[idx] -= val }
      end
    end
def render(svg, options = {})
      #TODO ensure this works with new points
      #current_points = points
      layers.each_with_index do |layer,i|
        
        #real_points = layer.points
        #layer.points = current_points
        layer_options = options.dup
 
        layer_options[:num_bars] = layers.size
        layer_options[:position] = i
        layer_options[:color] = layer.preferred_color || layer.color || options[:theme].next_color
        layer.render(svg, layer_options)
              
        options.merge(layer_options)
        
        #layer.points = real_points
        #layer.points.each_with_index { |val, idx| current_points[idx] -= val }
      end
    end
Returns new Multi graph.

 You can provide a block for easily adding layers during (just after) initialization.
 Example:
   Multi.new do |multi|
     multi << Scruffy::Layers::Line.new( ... )
     multi.add(:multi_bar, 'My Bar', [...])
   end

 The initialize method passes itself to the block, and since multi is a LayerContainer,
 layers can be added just as if they were being added to Graph.
 Overrides Base#render to fiddle with layers' points to achieve a multi effect.