Write some CI

[BenKaehler]

Would be good if we could automate checking that the weights and uploaded references can be used to build valid classifiers.

[BenKaehler]

The new scripts/self-consistency-check.sh does this but it takes too long (>24 hours, thanks SILVA full-length) to include as CI.

Anyone making changes to this repo should run scripts/self-consistency-check.sh and check the output before pushing.