Evaluate pooch

[Anthchirp]

Learnt of the existence of pooch at SciPy 2020.
This could be a potential new backend for dials-data dealing with downloading and unpacking and all that stuff.

[graeme-winter]

To my eyes this looks like it would do much of the work of dials.data? 🤔 seems real useful

[rjgildea]

It also looks to have support for zipped/compressed files:
https://www.fatiando.org/pooch/latest/usage.html#post-processing-hooks