Revert "replace external MathJax CDN with local offline-ready version (fixes …" (#598)

This reverts commit 0c1da0e.

Author: twalen

oioioi/base/templates/base.html

@@ -116,20 +116,7 @@
             <script>const oioioi_base_url = "{{ base_url | escapejs }}";</script>
             <script src="{% url 'javascript_catalog' %}"></script>
             <script src="{% static 'index.bundle.js' %}"></script>
-            <script>
-                window.MathJax = {
-                    tex: {
-                      inlineMath: [ ['$','$'], ['\\(','\\)'] ],
-                      displayMath: [ ['$$','$$'], ['\\[','\\]'] ],
-                      processEscapes: true
-                    },
-                    options: {
-                        ignoreHtmlClass: 'tex2jax_ignore',
-                        processHtmlClass: 'tex2jax_process'
-                    }
-                };
-            </script>
-            <script type="text/javascript" id="MathJax-script" src="{% static 'mathjax/tex-chtml.js' %}"></script>
-        {% endblock %}
+            <script async src="{{ mathjax_location }}MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script>
+       {% endblock %}
     </body>
 </html>

oioioi/default_settings.py

@@ -836,8 +836,9 @@
 # for new messages to notify about
 MAILNOTIFYD_INTERVAL = 60
 
-# Serve MathJax library from local static files
-MATHJAX_LOCATION = '/static/mathjax/tex-chtml.js'
+# If your contest has no access to the internet and you need MathJax typesetting,
+# either whitelist this link or download your own copy of MathJax and link it here.
+MATHJAX_LOCATION = "https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/"
 
 # Django message framework CSS classes
 # https://docs.djangoproject.com/en/1.9/ref/contrib/messages/#message-tags