custom components need to define a javascript-module
module-test is a very simple sample that just renders the data as
JSON to the dom node that is passed.
In early state component development this is helpful.

markdown rederers are available as js library or react library
we implemented a markdown viewer via a js library marked
because the react component did not work.

 MathJax has v2 and v3. v3 is breaking the v2 api.
es6 modules for the browser not working; this means browser 
will load mathjax to window/MathJax
so we ship the compiled mathjax.js bundle

   popover
placement: left, yop, right, bottom