Dataset variants

Created by: Zaharid

We have recently been taking the approach of never modifying existing datasets (which I think is a good thing) and instead adding fixed versions of them with different names. For example we have the so called *_SF sets, which stands for "symmetrization fix".

I find this approach to also be problematic. For one I seemed to be the only one at the meeting last week who seemed to know what these things are and that you should use them instead of the default ones. Also, all that might be documented somewhere, but I couldn't find it (admittedly I only spent 30 seconds searching but still).

I think a better approach would be to teach the code to know that there are variants of the various datasets (the variant used in 3.1 the variant that had a bug fixed and so on). And then have ways to warn you if you are using a deprecated variant or to know what the default variants are.

This ties with:

• The discussion on general metadata files.
• The discussion on defaults #226 (closed).
• The discussion on resources #224.