A concept for OGGM-Shop

[fmaussion]

This is really a WIP

But I already like it ;-)

[pep8speaks]

Hello @fmaussion! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

• In the file oggm/tests/test_shop.py:

Line 60:29: E127 continuation line over-indented for visual indent

Comment last updated at 2020-04-14 14:29:50 UTC

[fmaussion]

This is a first step toward a new module in oggm: oggm.shop. The functionality is quite poor at the moment but it will be extended.

Most use case atm is to start from an RGITOPO dem (cc @matthiasdusch). The rest will follow, mostly about adding climate and validation data to the folders, etc.