* Support for top-level \newline and \\ in inline math
This was a little tricky because `\\` was defined as an endOfExpression.
Instead made `\\` a termination specific to an array environment.
Outside an array environment, buildHTML handles the `cr` object,
resulting in a `.newline` class. Currently this turns into a
`display: block` (with appropriate vertical spacing) only in inline math,
matching LaTeX.
* Simplify code
* Fix Jest errors
* NewLine screenshot test
* Bug fix: \\ only works at top level of inline
* Add \newline and \cr to test
* Switch test to pmatrix
* Add vertical space test
* Add \\ vs. \newline tests
* Fix flow errors
* Add \cr test
* Add documentation for \\ at top level
* Comment out newRow
* Fix commenting out