Improve accessibility of event form

- use <label> tag instead of <legend>
- display time selectors on same line as date selector

src/Bundle/ChillEventBundle/Controller/ParticipationController.php

@@ -486,7 +486,7 @@ final class ParticipationController extends AbstractController
 
             return $this->redirectToRoute(
                 'chill_event__event_show',
-                ['event_id' => $event->getId()]
+                ['id' => $event->getId()]
             );
         }