restore original mathjaxhelper.js

docs/scripts/mathjaxhelper.js

 MathJax.Hub.Config({
-  jax: ["input/TeX" , "output/CommonHTML"],
+  config: ["MMLorHTML.js"],
+  jax: ["input/TeX", "output/HTML-CSS", "output/NativeMML"],
   tex2jax: {
     inlineMath: [ ['$','$'] ],
     processEscapes: true
   },
   extensions: ["MathMenu.js", "MathZoom.js"]
 });
-