title: Twig always returns blank page
body: <p>Hey everybody I am just trying to learn Twig and having a problem getting it to work at all. There are no errors returned in the web server or on the CLI but it just doesn't render the template at all. I installed twig using composer.</p>
  
  <pre><code>&lt;?php
  require_once 'vendor/autoload.php';
  class xltwig {
          private static $twig;
          public static function twig() {
                  $templateDir = __DIR__.'/twig/en_us';
                  if ( ! isset(self::$twig) ) {
                          $loader = new Twig_Loader_Filesystem(array($templateDir));
                          self::$twig = new Twig_Environment($loader);
                  }
                  return self::$twig;
          }
  }
  $twig = xltwig::twig();
  $twig-&gt;render("index.html",array('pageTitle' =&gt; 'test'));`
  </code></pre>
  
  <p>index.html is simply:</p>
  
  <pre><code>&lt;h1&gt;{{ pageTitle }}&lt;/h1&gt;
  </code></pre>