Make consistant with the GitHub implementation

[mwt]

GitHub now supports $ and $$ in md and rst files. However, as you may have noticed from your readme, they require two backslashes in display mode for rst file. So, \frac{a}{b} is rendered as $frac{a}{b}$ and \\frac{a}{b} is rendered as $\frac{a}{b}$.

This may not be intentional. I've created an issue here about this:
github/markup/issues/1554

Because consistent formatting with GitHub may be a major use case for this plugin going forward, I thought it sensible to track this. Many projects use readme.rst files in exactly the same way that you do in this repo and a fix like this could allow you to remove your aside:

(if you are reading this on GitHub, look at the version built by Sphinx here)

[asmeurer]

Does the GitHub implementation work in RST? I thought it was Markdown only.

As far as I know, this extension is the only way to get math with dollar signs in RST. Ideally if GitHub is going to support dollar math in RST (and even in Markdown), they should not require double backslashes, as this is not standard anywhere else except in environments where backslashes are already used as escape characters (like in Python strings).

I don't know if we can even support both double and single backslashes unambiguously, since a double backslash already means newline in LaTeX.

[asmeurer]

Just saw that it is working in the README. That's quite interesting and probably worth mentioning in the docs somewhere. That makes this extension much more powerful. I wonder if they also support the normal RST :math:`\sin(x)` or .. math::.

Either way, the double backslash thing definitely looks like a bug on GitHub's end, and like I said, I don't even know if we can unambiguously support it. I did notice some other bugs in GitHub's implementation relating to backslashes (e.g., they render things like \, and \: incorrectly, like \int x\, dx renders as $\int x, dx$). I think they just need to fix up their parser. Hopefully they will do so soon before people start "working around" these bugs in it too much.

[mwt]

I wonder if they also support the normal RST :math:`\sin(x)` or .. math::.

They do not 😢. I asked if they could in github/markup/issues/83...

Either way, the double backslash thing definitely looks like a bug on GitHub's end, and like I said, I don't even know if we can unambiguously support it. I did notice some other bugs in GitHub's implementation relating to backslashes (e.g., they render things like \, and \: incorrectly, like \int x\, dx renders as ∫x,dx). I think they just need to fix up their parser. Hopefully they will do so soon before people start "working around" these bugs in it too much.

I definitely agree! I hope it doesn't stay like this for years. If it does, they might never fix it (and risk breaking the rsts of people who used the workaround).