Add functions to save and open dataset

[Billyzhang1229]

• Add save_dataset/load_dataset to support on-disk Zarr storage #37

[coveralls]

Pull Request Test Coverage Report for Build 3099046953

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 12 of 14 (85.71%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.3%) to 97.2%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
phylokit/dataset.py	10	12	83.33%

Totals
Change from base Build 2954999796:	-0.3%
Covered Lines:	486
Relevant Lines:	500

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💛 - Coveralls

[jeromekelleher]

Looks like a bunch of unrelated parsimony stuff included here. Simplest thing would be to rebase this PR on upstream/main and to drop all but the last commit. (But make sure you have a backup of these commits on another branch!)

[jeromekelleher]

Looks good, a few small tweaks needed + better testing.

[jeromekelleher]

LGTM!