Migrate tutorial content to tskit.dev/tutorials in jupyterbook format

[jeromekelleher]

The "tutorial" section in the tskit docs has always been a bit of a mess. We should migrate the content to more focused tutorials at https://github.com/tskit-dev/tutorials (e.g., tskit-dev/tutorials#19, and tskit-dev/tutorials#18).

[hyanwong]

I'm starting to do this. AFAICS there are 5 blocks of content in the "tutorial" section:

1. Trees (including iterating over them)
2. Tables - including editing a TS
3. Metadata
4. TS analysis (LD, computing stats, AFS + probably working with threads)
5. Parsimony

3 (Metadata) is done as a new tute in tskit-dev/tutorials#74,

1 and 2 have been transferred into the "data-structures" tut in tskit-dev/tutorials#75

4 should, I think be an easy win (tskit-dev/tutorials#72)

That only leaves 5: Parsimony. I wonder if this also goes with the combinatorics tutorial material (e.g. #670), perhaps a tute called "phylogenetic methods", along with an example of the fancy numba stuff. But maybe that's a bit too disparate a set of ideas to put into one tutorial.

[hyanwong]

This is now all sorted. Once tskit-dev/tutorials#88 is sorted I'll push a PR to tskit to delete the tutorial page and close this issue.