def initialize(drawing, options={})
      @drawing = drawing
      drawing.anchors << self
      @from, @to =  Marker.new, Marker.new(:col => 5, :row=>10)
      parse_options options

      # bit of a hack to work around the fact that the coords for start at and end at
      # are passed in as an array when specified in intialization options - however
      start_at(*options[:start_at]) if options[:start_at]
      end_at(*options[:end_at]) if options[:end_at]
    end
Creates a new TwoCellAnchor object
c.start_at 5, 9
@param [Drawing] drawing
@option options [Array] :start_at the col, row to start at THIS IS DOCUMENTED BUT NOT IMPLEMENTED HERE!
@option options [Array] :end_at the col, row to end at