Implement math typesetting using OpenType math fonts

- https://github.com/notofonts/math/blob/main/documentation/building-math-fonts/index.md
- https://learn.microsoft.com/en-us/typography/cleartype/pdfs/cambriamath.pdf
- https://www.w3.org/TR/mathml-core/
- https://tug.org/TUGboat/tb27-1/tb86jackowski.pdf
- https://www.tug.org/~vieth/papers/bachotex2009/ot-math-paper.pdf