title: how do i include a tpl file in my module drupal 7
body: <p>I'm building a module using hook_preprocess_node()
  I've made a new view mode for the node entity called ´vacancy_teaser´ using the hook_entity_info_alter()</p>
  
  <p>this shows up in my node display settings and view</p>
  
  <p>so I want to use the template included in my module when this view mode is used.</p>
  
  <p>my code:</p>
  
  <pre><code>/**
  * Implements hook_preprocess_node().
  */
  function vacancies_preprocess_node(&amp;$vars) {
    if($vars['view_mode'] == 'vacancy_teaser') {
      $vars['theme_hook_suggestions'][] = 'node_vacancy_teaser';
    }
  } 
  </code></pre>
  
  <p>my template file is called: ´node-vacancy-teaser.tpl.php´ but is not used in the output of my view
  <code>$vars['view_mode'] == 'vacancy_teaser'</code> in the view. ( tested )</p>
  
  <p>but where does <code>$vars['theme_hook_suggestions'][] = 'node_vacancy_teaser';</code> looks for the template file? somehow it's not included / used.</p>
  
  <p>apparently in drupal 7 useing dubble underscores is required for some reason.
  node_<em>vacatures</em>_vacancy_teaser.tpl.php placed in the active template folder seems to do the trick... although I don't think this is a neat solution since the tpl.php file is separated from the module.</p>