def initialize(frame, options={})
      @style = 18
      @view_3D = nil
      @graphic_frame=frame
      @graphic_frame.anchor.drawing.worksheet.workbook.charts << self
      @series = SimpleTypedList.new Series
      @show_legend = true
      @legend_position = :r
      @display_blanks_as = :gap
      @series_type = Series
      @title = Title.new
      @bg_color = nil
      parse_options options
      start_at(*options[:start_at]) if options[:start_at]
      end_at(*options[:end_at]) if options[:end_at]
      yield self if block_given?
    end
Creates a new chart object
@param [GraphicalFrame] frame The frame that holds this chart.
@option options [Cell, String] title
@option options [Boolean] show_legend
@option options [Symbol] legend_position
@option options [Array|String|Cell] start_at The X, Y coordinates defining the top left corner of the chart.
@option options [Array|String|Cell] end_at The X, Y coordinates defining the bottom right corner of the chart.