RFE: Provide a LaTeXML-maybeCSS.js script

[fred-wang]

Same as maybeMathJax but instead of inserting a script tag it does

            var link = document.createElement("link");
            link.href = "http://fred-wang.github.io/mathml.css/mathml.css";
            link.rel = "stylesheet";
            document.head.appendChild(link);

[brucemiller]

I like the sentiment, but not so sure about the details. Firstly, I'm pretty sceptical about handling MathML with CSS, other than small subsets; bad experiences in the past. But also, I'm concerned about folks inadvertently introducing a dependence on a github repo into a "live" website. It's bad enough depending on MathJax's CDN, but at least is more explicit (& yes, I understand the advantage of continuous updates).

Once we get our enhanced config & plugin setup working, this would be simple to do as a plugin, and you could even (optionally?) include the current css along with it.