* FEATURE: Add KaTeX in-browser rendering support.
* Remove ttf fonts from KaTeX
* Update KaTeX to v0.10.1, fix paths to fonts.
Font loading was fixed by rebuilding KaTeX
and specifiying absolute paths to fonts in CSS:
Steps to build KaTeX:
1. `git clone https://github.com/KaTeX/KaTeX.git && cd KaTeX`
`git submodule update --init --recursive`
2. Change paths to fonts:
`sed -ri 's/@font-folder.+$/@font-folder:
"\/plugins\/discourse-math\/katex\/fonts";/'
submodules/katex-fonts/fonts.less`
3. Disable TTF fonts:
`export USE_TTF=false`
Alternatively, we could modify `.browserslistrc` to match what
Discourse supports
3. Build KaTeX
`yarn && yarn builld`
4. Copy `katex.min.js` and `katex.min.css` from `dist/` to
`discourse-math/public/katex/`
5. Update fonts, copy woff and woff2 files from
`submodules/katex-fonts/fonts`
* Minor copy edit to settings
Mark MathKJax only settings
* Add Mhchem extension for KaTeX.
It is already automatically loaded for MathJaX.
