examples: simplified author disambiguation

[glouppe]

Work-in-progress for a simplified author disambiguation example.

This example will basically be factored out of https://gist.github.com/glouppe/edaee2c0f82745e301de

• [x] Semi-supervised learning for clustering
• [x] Disambiguation example
• [x] Better affinity function for signatures
• [x] Narrative documentation of the example
• [x] Add tests for beard.utils.strings

[glouppe]

I have just to add a few tests for beard.utils.strings, but otherwise this thing is ready for reviews.

[glouppe]

CC @etzemis @petros-ioannidis @MSusik Please feel free to experiment yourself with the example. Suggestions are welcome.

[glouppe]

Added last tests for asciify. This is now ready.

[MSusik]

When the test pass, I will give you an :+1:

[glouppe]

Test now pass. Thanks @MSusik for the review! (This asciify function could be made more robust though...)

[glouppe]

@etzemis @petros-ioannidis Could one of you review as well?

[etzemis]

Reviewed. No objections :+1:

[glouppe]

Great! Thanks @etzemis