Add option to disable inline math

[morganwillcock]

This adds the sphinx option m2r_disable_inline_math and the cli option --disable-inline-math.

Previously there was no way to disable interpreting anything between two $ characters as math. An example of a problematic document is something like this, where we are having rendering issues due to the inline math parsing being triggered by page content.

I've not really looked at anything similar before, so feel free to edit or reject for a different approach.

Thanks!

[codecov-io]

Codecov Report

Merging #28 into master will increase coverage by 0.09%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #28      +/-   ##
==========================================
+ Coverage   96.16%   96.25%   +0.09%     
==========================================
  Files           3        3              
  Lines         756      775      +19     
==========================================
+ Hits          727      746      +19     
  Misses         29       29

Impacted Files	Coverage Δ
tests/test_cli.py	95.68% <100%> (+0.31%)	⬆️
m2r.py	93.51% <100%> (+0.14%)	⬆️
tests/test_renderer.py	99.1% <100%> (+0.01%)	⬆️

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[adeelsohailahmed]

Hey @miyakogi, why don't you check out this awesome pull request by morganwillcock? It fixes a fundamental issue.

[miyakogi]

Sorry for late response.
I was wondering this may be a specific use case.
But some people agree this PR, I decided to merge this.
Thank you for nice code and tests!

[kalvdans]

I suggest we remove support for inline math using

`$ a=b $`

and replace it with

$` a=b `$

and revert this PR, since the flag is not needed anymore. I've posted issue CrossNox#20 about it.

[morganwillcock]

The use case isn't for how to use inline math, it is how to work around valid Markdown (the specification for which has no concept of inline math) being interpreted as inline math. This option is effectively an extension which indirectly creates a Markdown derivative, so there should be an option to control whether it is active.

A good modification might be one that allowed you to specify the inline math style that you wanted to use, as well as turn it off.

[kalvdans]

I agree, given the plethora of syntaxes discussed at https://talk.commonmark.org/t/mathjax-extension-for-latex-equations/698 . The first step is to remove the current syntax and the flag though, to prepare for adding another option that specifies the inline math style.