Add homework links to lesson back pages

Fixes: #256

Author: encukou

naucse/templates/coverpage.html

@@ -36,6 +36,11 @@ <h2>Taháky</h2>
             {{ material_list(session.materials, filter_type='cheatsheet') }}
         {% endif %}
 
+        {% if homework_section %}
+            <h2>Domácí projekty</h2>
+            {{ material_list(session.materials, filter_type='homework') }}
+        {% endif %}
+
         {% block coverpage_content %}
             {{ content }}
         {% endblock %}