This PR implements `\mathchoice` function.
I once created PR on the wrong branch. Sorry for the mess.
This is particularly useful when one defines custom macro for "big operators".
For example:
```latex
\newcommand{\infdisj}{%
\mathop{%
\mathchoice{% display
\bigvee\hspace{-2ex}\bigvee%
}{ % inline
\bigvee\hspace{-1.75ex}\bigvee%
}{ % script
\bigvee\hspace{-1.4ex}\bigvee%
}{ % scriptscript
\bigvee\hspace{-1ex}\bigvee%
}}}
```
* Support \colorbox and \\fcolorbox
These are functions from the `color` package. They accept text, not math. They also have padding similar to `\fbox`.
Because of the padding, the code in `buildHTML` is intermixed with the `\fbox` code. I have not (yet) created a new file in the functions folder. This way, the reviewer gets a cleaner diff.
* Fix lint error
* colorbox screenshots
* Pick up review comments
Summary: (@kevinbarabash)
This diff extracts MathML builder tests out into a separate file and
updates them to use jest snapshot testing. It updates the output of
prime ' from using identifier nodes <mi> to operator nodes <mo>. It
also updates large operators with limits to use munderover instead
of msupsub. I added an option to remove unnecessary mrows to buildGroup.
Right now it's only used for by groupTypes.supsub. I'll see if it can be used
elsewhere (everywhere?) in a follow up PR.
Test Plan:
- make test w/o errors
- verify mathml snapshots contain the desired markup
