title: hidden column issue with Datatables
body: <p>I have rendered a hidden column using the fnRender function like this</p>
  
  <p><code>"aTargets": [0],<br>
   "fnRender": function ( oObj ) {<br>
                   return '&lt;input id="test" name="test" value="'+ oObj.aData[0] +'" type="hidden" /&gt;';<br>
   }
  </code></p>
  
  <p>and under <code>aoColumns</code> have defined <code>null</code> for it.</p>
  
  <p>Now this field shows up as a column in the Datatables, which I do not want.</p>
  
  <p>I tried the attribute <code>bVisible:false</code> , but that also removes it from rendering , hence I am unable to get the value from the hidden field.</p>
  
  <p>Please help.</p>