Merge branch '4.0' into 4.1

* 4.0:
  More fixes about Twig classes namespaces

Author: javiereguiluz

best_practices/templates.rst

@@ -74,7 +74,7 @@ to define one single method to transform Markdown content into HTML::
     }
 
 Next, create a new Twig extension and define a filter called ``md2html`` using
-the ``TwigFilter`` class. Inject the newly defined ``Markdown`` class in the
+the ``Twig\TwigFilter`` class. Inject the newly defined ``Markdown`` class in the
 constructor of the Twig extension::
 
     namespace App\Twig;