Support Twig extension i18n

composer.json

@@ -30,7 +30,8 @@
         "simplesamlphp/saml2": "dev-master#00e38f85b417be1e10a2d738dd2f5ea82edb472c as 2.2",
         "robrichards/xmlseclibs": "~2.0",
         "whitehat101/apr1-md5": "~1.0",
-        "twig/twig": "~1.0"
+        "twig/twig": "~1.0",
+        "twig/extensions": "^1.3"
     },
     "require-dev": {
         "ext-pdo_sqlite": "*",

config-templates/config.php

@@ -649,6 +649,11 @@ $config = array(
     'language.cookie.lifetime' => (60 * 60 * 24 * 900),
 
     /*
+     * Which i18n backend to use
+     */
+    'language.i18n.backend' => 'twig.i18n',
+
+    /**
      * Custom getLanguage function called from SimpleSAML\Locale\Language::getLanguage().
      * Function should return language code of one of the available languages or NULL.
      * See SimpleSAML\Locale\Language::getLanguage() source code for more info.