Rename twig to Twig to get it working.

resources/templates/engine/Twig/Node/Expression/Constant.php

@@ -0,0 +1,23 @@
+<?php
+
+/*
+ * This file is part of Twig.
+ *
+ * (c) 2009 Fabien Potencier
+ * (c) 2009 Armin Ronacher
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+class Twig_Node_Expression_Constant extends Twig_Node_Expression
+{
+    public function __construct($value, $lineno)
+    {
+        parent::__construct(array(), array('value' => $value), $lineno);
+    }
+
+    public function compile(Twig_Compiler $compiler)
+    {
+        $compiler->repr($this->getAttribute('value'));
+    }
+}