title: jinja2 filesystemloader load all subdirectories
body: <p>I currently have templates in multiple different sub directories and I would like to load all of the templates in jinja2. It appears that just pointing the FileSystemLoader directory at the top of the tree doesn't pick up anything in the sub folders.</p>
  
  <p>Is there a way to get jinja2 to load all of the sub directories (just a single level down is ok but the whole tree would be preferable)?</p>
  
  <p>So far I've managed to do this with a choice loader:</p>
  
  <pre><code>sub_dirs = [os.path.join(template_file_root,dirname) for dirname in os.listdir(template_file_root) 
  \ if os.path.isdir(os.path.join(template_file_root, dirname))]
  
  jinja_dirs = [ jinja2.FileSystemLoader(dirname) for dirname in sub_dirs ]
  
  template_env = jinja2.Environment (loader = jinja2.ChoiceLoader(jinja_dirs))
  </code></pre>
  
  <p>However this seems a little hacky. Any better suggestions?</p>