[FR] Estimations of `ε`

Would be great if we had a function with various methods to estimate ε , the threshold of a recurrence plot.

This could work similarly with estimate_delay which gives delay times for timeseries.

Different methods are described in the book from N. Marwan and citations within, see chapter 1 (we cite the book in most docs). Some of these methods are actually very easy and straightforward and would be a great issue for newcomer contributor.