title: using TwigTrait in silex
body: <p>I'm using silex for one of my projects and usually when  i want render a twig template I use this syntax :</p>
  
  <pre><code>$app['twig']-&gt;render('page.twig');
  </code></pre>
  
  <p>in this project I want to use the trait to have this syntax :</p>
  
  <pre><code>$app-&gt;render('page.twig');
  </code></pre>
  
  <p>to do that I modified the Application class in Silex\Application and added :</p>
  
  <pre><code>use TwigTrait;
  </code></pre>
  
  <p>so my question is : if its ok to do that and modify this class or if not, is there another way to do that.</p>
  
  <p>thanks in advance and I apologize for my bad English.</p>