Henri Menke

Looking around in the code the entire ConTeXt pgfutil could do with some refactoring. For example the gray colormodel just maps to rgb.

I'd like to have a few ConTeXt tests before merging this so it is essentially also blocked by #1116 (or rather an extension thereof).

LMTX is currently not supported because it removed too many primitives.

This is actually harder than I had anticipated, because the code of the externalization library is mostly unreadable gibberish.

Don't bother. `\draw ... circle (...)` is fully supported and will always be supported in the future. It is way too popular to ever be deprecated or removed.

Forgot to handle `calc`. In that case, I can also go the extra mile and loop over expansions.

As always, thanks for your very insightful input. You are definitely right. We have to promote `coordinate` to a first class member of the syntax instead of rewriting it to...

Related issues are #958 and #989

Duplicate of https://github.com/pgf-tikz/pgf/issues/850

This PR is blocked by #1116.