tidy trailing slash everywhere & fix tests

templates/pagenotfound.html

@@ -41,7 +41,8 @@ Did you mistype the URL '<b>{{ path }}</b>' ?
 {% endif %}
 <p>
  <p>
- <p>Did you get lost ?</p>
+ <h3>Did you get lost on the plateau?</h3>
+<p>
  
  <img align=center src="/handbook/i/204-area.png">
 {% include "menu.html" %}