Add support for LaTeX math expressions

[anschmieg]

Issue Description
Currently, the HTML output displays e.g. the example entry

Built an app to compute the similarity of all methods
in a codebase, reducing the time from $$\mathcal{O}(n^2)$$
to $$\mathcal{O}(n \log n)$$

as a literal, without rendering the math expression.

Suggested change
By adding Mathjax to the document via the Cloudflare CDN, LaTeX and LaTeX math expressions get parsed correctly if the CDN is reachable.

---

I hope I didn't screw up the branches or the commit history again... still working those out 😄

[anschmieg]

Since there is still an AssertionError, I assume the HTML output doesn't match the expected result because of the added tag?

Edit: committed modification of the relevant tests