added charset as a parameter

doc/services.rst

@@ -263,3 +263,7 @@ Core parameters
   debug mode.
 
   Defaults to false.
+
+* **charset** (optional): The charset to use for Responses.
+
+  Defaults to UTF-8.

src/Silex/Application.php

@@ -96,6 +96,7 @@ class Application extends \Pimple implements HttpKernelInterface, EventSubscribe
         $this['request.http_port'] = 80;
         $this['request.https_port'] = 443;
         $this['debug'] = false;
+        $this['charset'] = 'UTF-8';
     }
 
     /**

src/Silex/Extension/TwigExtension.php

@@ -28,7 +28,12 @@ class TwigExtension implements ExtensionInterface
     public function register(Application $app)
     {
         $app['twig'] = $app->share(function () use ($app) {
-            $twig = new \Twig_Environment($app['twig.loader'], isset($app['twig.options']) ? $app['twig.options'] : array());
+            $app['twig.options'] = array_replace(
+                array('charset' => $app['charset']),
+                isset($app['twig.options']) ? $app['twig.options'] : array()
+            );
+
+            $twig = new \Twig_Environment($app['twig.loader'], $app['twig.options']);
             $twig->addGlobal('app', $app);
 
             if (isset($app['symfony_bridges'])) {