Make getEntityDisplayName available as a filter

lib/SimpleSAML/IdP.php

@@ -169,7 +169,7 @@ class IdP
 
     /**
      * Get SP name.
-     * Only usefd in IFrameLogout it seems.
+     * Only used in IFrameLogout it seems.
      * TODO: probably replace with template Template::getEntityDisplayName()
      *
      * @param string $assocId The association identifier.

lib/SimpleSAML/XHTML/Template.php

@@ -325,6 +325,13 @@ class Template extends Response
                 ['needs_context' => true]
             )
         );
+        // add a filter for preferred entity name
+        $twig->addFilter(
+            new TwigFilter(
+                'entityDisplayName',
+                [$this, 'getEntityDisplayName'],
+            )
+        );
 
         // add an asset() function
         $twig->addFunction(new TwigFunction('asset', [$this, 'asset']));