Enable MathJax in HTML docs

Doxyfile

@@ -1681,7 +1681,7 @@ FORMULA_MACROFILE      =
 # The default value is: NO.
 # This tag requires that the tag GENERATE_HTML is set to YES.
 
-USE_MATHJAX            = NO
+USE_MATHJAX            = YES
 
 # With MATHJAX_VERSION it is possible to specify the MathJax version to be used.
 # Note that the different versions of MathJax have different requirements with