[smartsyntax] converting lines with leading "// " to <div class="comment">
[incubator] added css styling for waiting for mathjax (need js still)
[incubator] removing mathjaxwait class from container once mathjax finished processing the elements

the trick is to have all elements display:!none when mathjax runs,
then we can display:none all unshown elements which is good for performance (firefox especially)
 and also for avoiding duplicate ids shown at the same time (e.g., in SVG)
     (works well with chrome, still a duplicate id with firefox even if not displayed)