Add an example notebook showcasing replicability analysis to aid component selection

[blzserdos]

Following up on #8 and heavily based on tensorly/viz#24 (comment), i've added an example notebook describing 'component selection via replicability analysis for PARAFAC2' to the Gallery of examples. The notebook takes approx. 10 min to execute due to the large number of models being ran. Normally, these would be run in parallel, but i think this should be ok for demonstration?

@cchatzis

Please let me know what you think!

[MarieRoald]

This looks really good, just a couple of minor tweaks here and there. Regarding the build time, that will be a problem, and I'm pretty sure the build process will time out. As I see it, there are two ways around it:

1. Have this as an example notebook instead of a example script. The notebooks are not run when we build, but then we wouldn't be able to keep the citation in the reference list.
2. Commit the build artifacts in docs/auto_examples the plot_replicability.py-file. This will make it so we don't need to run the example when we build the docs, but we would loose the nice separation where the example gallery is automatically built and the notebooks are manually built.

I think I preffer solution 2, which would require running git add ./docs/auto_examples/plot_replicability* -f to forcefully add the sphinx-gallery build artifacts, but it's up to you :)

[blzserdos]

Thanks a lot for the scrutiny and the great suggestions. I went with the suggested option 2. Please let me know what you think!

[MarieRoald]

Great job! I just have a couple of small suggestions, and after that you just need to rebuild the docs and commit the updated replicability-files in the auto_examples directory before we can merge :)

[cchatzis]

Should be OK now! Thanks a lot for the further comments @MarieRoald !

[MarieRoald]

Great, thanks for the nice contribution @blzserdos and @cchatzis !