title: Using helper getTagItemsQuery needs alias ids not actual aliases
body: <p>I am writing a module to display tags and I'm using the JHelper method getTagItemsQuery.</p>
  
  <p>In the documentation it states that the second parameter should be a content alias (eg. 'com_content.article' ) but from what I can see in the code, it assumes that the second parameter is a content type id.
  So for example, this returns a valid query</p>
  
  <pre><code>$query = $tags-&gt;getTagItemsQuery( 2 , 1, true, 'c.core_publish_up', 'DESC', true, 'all', '1' );
  </code></pre>
  
  <p>But this does not:</p>
  
  <pre><code>$query = $tags-&gt;getTagItemsQuery( 2 , 'com_content.article', true, 'c.core_publish_up', 'DESC', true, 'all', '1' );
  </code></pre>
  
  <p>(the resulting query has an empty IN statement)</p>
  
  <p>On line 596 of the code it seems to explicity assume that the second parameter ($typesr) is an id, not an alias</p>
  
  <pre><code>$typesarray = self::getTypes('assocList', $typesr, false);
  </code></pre>
  
  <p>Is this an error in the documentation for getTagItemsQuery, or have I misunderstood how it should be used?</p>