title: Dgrid: ColumnHider plugin's 'hidden' property not taking effect
body: <p>I have a column with with both 'hidden' &amp; 'unhidable' set to true. However, the column does not hide....upon doing some testing, I found that it hides only when unhidable is set to false.</p>
  
  <p>i.e.,</p>
  
  <pre><code>hidden: true,
  unhidable: true
  </code></pre>
  
  <p>doesn't work</p>
  
  <pre><code>hidden: true,
  unhidable: false
  </code></pre>
  
  <p>works</p>
  
  <p>Is it not possible to have both hidden &amp; unhidable as true?</p>
  
  <p>FYI, I'm also using the ColumnResizer &amp; DijitRegistry plugins. This is the column definition from the grid template:</p>
  
  <pre><code>&lt;th data-dgrid-column='{
          field: "order",
          hidden: true,
          unhidable: true,
          sortable: false
          }'&gt;
          Order
  &lt;/th&gt;
  </code></pre>