Hopf torus

[stla]

An example: a Hopf torus with a dynamic texture (#2078).

[github-actions]

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[MatthewFlamm]

Windows testing is broken currently but is hopefully fixed in #2137. Don't worry about those checks

[banesullivan]

Hi @stla, thank you for your contributions!! Please disregard the Pull Request Labeler / triage (pull_request) check

[adeak]

This is awesome! Thanks for posting this.

Aside from the below hard suggestions for trivial typo-grade nitpicks I only have a few general remarks, none of which are crucial:

1. I'd probably use np.pi if we already have NumPy imported.
2. I think (hope) our examples quite rigorously follow the snake_case function naming convention of the library, so perhaps that would make this example fit even more in.
3. This is 100% subjective, but I loved the "nipy_spectral" version from your discussion post a lot. The flag colormap version seems a bit trippy to me, I could maybe imagine people being uncomfortable looking at it. But the nipy_spectral is very calm and smooth.

Again, none of these are crucial. This is an excellent example as is.

[adeak]

Looks great, thanks again @stla.