title: Twig i18n : Unexpected tag name "trans"
body: <p>I'm trying to do some i18n on some Twig templates. The relevant code in index.php is as follows :</p>
  
  <pre><code>// Twig
  $app-&gt;register(new Silex\Provider\TwigServiceProvider(), array(
      'twig.path' =&gt; __DIR__ . '/../src/views',
  ));
  $twig = new \Twig_Environment($app['twig.loader.filesystem']);
  $twig-&gt;addExtension(new \Twig_Extensions_Extension_I18n());
  
  // User Controller Service Provider for SimpleUser
  $app-&gt;register($u = new SimpleUser\UserServiceProvider());
  $app['twig.loader.filesystem']-&gt;addPath(__DIR__.'/../src/views/user','user');
  $app['user.controller']-&gt;setLayoutTemplate('layout.twig');
  $app-&gt;mount('/silex-ror/user', $u);
  </code></pre>
  
  <p>Then, in the twig template being rendered I wrote :</p>
  
  <pre><code>&lt;h1&gt;{% trans %}List users{% endtrans %}&lt;/h1&gt;
  </code></pre>
  
  <p>But I get an error :</p>
  
  <pre><code>Unexpected tag name "trans"
  </code></pre>
  
  <p>Since I don't get any error when adding the extension, I assume it's simply being completely ignored when I try to render the template, but I'm not sure where I'm making a mistake.</p>
  
  <p>Any help appreciated.</p>