Modified guessDefaultEscapingStrategy to not escape txt templates

Useful for plaintext emails.

Author: maryo

src/Symfony/Bundle/TwigBundle/TwigEngine.php

@@ -57,6 +57,10 @@ public function guessDefaultEscapingStrategy($filename)
         if ('js' === $format) {
             return 'js';
         }
+        
+        if ('txt' === $format) {
+            return false;
+        }
 
         return 'html';
     }