title: Highcharts drilldown from a series
body: <p>I have a chart that displays series data by year.
  eg 1011, 1112, 1213, 1415, and shows an actual and target for each year.</p>
  
  <p>If the user clicks on a column, the chart drills down into that dataset, however I'd like to be able to show Actual and Target next to each other, rather than a single column...</p>
  
  <p>JSFiddle: <a href="http://jsfiddle.net/MuydK/" rel="nofollow">http://jsfiddle.net/MuydK/</a></p>
  
  <p>Any help appreciated, am stumped on this as tried several methods. 
  I believe I understand how to set up the data into a series set rather than just a dataset, but don't know what changes I need to make to SetChart etc...</p>
  
  <p>Also the Series titles disappear once I've drilled in and out once, any ideas...?</p>
  
  <p>Many Thanks for you help.</p>
  
  <pre><code>        var chart;
      $(document).ready(function () {
          var colors = Highcharts.getOptions().colors,
          categories1 = ['1011', '1112', '1213', '1415'],
          name1 = 'Actual',
  
          data1 = [ ...
  </code></pre>