Clean up stray elements created by MathJax
Clean up stray elements created by MathJax

Otherwise React will raise "Invariant Violation" exceptions when it notices them.

Also implement componentDidUpdate so the HTML will be reprocessed if it's content is updated

openstax/tutor-js,openstax/tutor-js,openstax/tutor-js,openstax/tutor-js,openstax/tutor-js