Conference URLs now use slugs instead of integer id

templates/base.html.twig

@@ -16,7 +16,7 @@
             <h1><a href="{{ path('homepage') }}">Guestbook</a></h1>
             <ul>
             {%for conference in conferences %}
-                <li><a href="{{ path('conference', { id: conference.id }) }}">{{ conference }}</a></li>
+                <li><a href="{{ path('conference', { slug: conference.slug }) }}">{{ conference }}</a></li>
             {% endfor %}
             </ul>
             <hr/>