title: Why is yadcf custom_filter not working?
body: <p>Fiddle: <a href="https://codepen.io/MBaas/pen/rpZZzd" rel="nofollow noreferrer">https://codepen.io/MBaas/pen/rpZZzd</a></p>
  
  <p>I have a Datatable about newspapers endorsements for presidential candidates that I want to filter on the party - a value that is not contained in the table (I have shortcodes "D" or "R" in the table but would like to use text "Democrat" or "Republican" in the UI).
  This may have once worked (I think it did) - but after upgrading to beta 0.9.1 it stopped. Possibly a bug in the beta - or possibly an undetected bug in my code?</p>
  
  <p>My fn:</p>
  
  <pre><code>function myCustomFilterFunction(filterVal,columnVal,rowValues,stateVal)
   {
   console.log(rowValues);
   console.log(filterVal+'/'+columnVal);
   if (columnVal === '') { return true;}
   return -1 &lt; columnVal.search(filterVal);
   }
  </code></pre>
  
  <p>I had added the <code>log</code> for debugging purposes and it produced this output (excerpt):</p>
  
  <pre><code>["Wisconsin State Journal", "2016", "Clinton", "", "", "", ""]
  "D/"
  </code></pre>
  
  <p>I was surprised to see <code>columnVal</code> being empty. That explained filtering not working, and it being empty can be explained by looking at <code>rowValues</code>. But given that the source-data was defined in JSON as </p>
  
  <pre><code>["Wisconsin State Journal",2016,"Clinton","http:\/\/host.madison.com\/wsj\/opinion\/editorial\/our-endorsement-hillary-clinton-america-must-get-this-right\/article_b526fe64-c2ca-5e3d-807a-0ef4ae23a4d5.html","","","D"]
  </code></pre>
  
  <p>this is odd. Could it be related to the fact that the column is not visible?</p>