Support typst

[ayykamp]

Add a mode for typst, a new open source typesetting system. Similar to https://github.com/QuarticCat/detypify

[FineFindus]

Thanks for the suggestion. I'm not against including the feature, but there are a few things to consider:

• Is there enough demand to justify the increased maintenance and code complexity (I don't use it myself [yet])?
• How well do the currently supported symbols map to the typed ones (I assume they use the same/similar symbol)?
• How well does the automatic mapping between commands work?
  I'll try to investigate some of these as soon as I have more time, though it may take a while.