title: Add additional data to a Highcharts series for use in formatters
body: <p>My question is exactly the same as the OP in this question:</p>
  
  <p><a href="https://stackoverflow.com/questions/8514457/set-additional-data-to-highcharts-series">Set Additional Data to highcharts series</a></p>
  
  <p>But the accepted answer explains how to add additional data to the <em>point</em>, not the series, without saying if it's possible to do with the series or not.</p>
  
  <p>I would like to be able to define a series like:</p>
  
  <pre><code>series: [
      {"hasCustomFlag": true, "name": "s1", "data": [...]},
      {"hasCustomFlag": false, "name": "s2", "data": [...]},
  ]
  </code></pre>
  
  <p>and be able to use <code>point.series.hasCustomFlag</code> inside of a formatting function.  Is this possible?</p>
  
  <p>I don't want to put the data on the point level, because that means I'd have to duplicate the data far too many times.</p>