Added support to download example datasets

[rjoberon]

Dear Sebastian,

Inspired by other libraries (e.g., Seaborn and scikit-learn) I have added support to download exemplary contexts from the repository https://github.com/fcatools/contexts. For more context, please have a look at this post on the FCA mailing list.

We can discuss details on how to properly handle, curate and implement this but I hope you like the idea. I'd happily make you (co)owner of the conexts repo or https://github.com/orgs/fcatools/ such that you have control over what can be loaded.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 100.00%. Comparing base (90214c2) to head (6890a51).

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Additional details and impacted files

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  Coverage   100.00%   100.00%           
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  Files           23        24    +1     
  Lines         1462      1471    +9     
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+ Hits          1462      1471    +9     

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[xflr6]

Thanks for the PR.

We can discuss details on how to properly handle, curate and implement this but I hope you like the idea.

Of course :) In recent times, I did not have much time for my open source projects but it would still be nice to make at least some small improvements.