Disallow inferred equivalencies when reasoning.

[gouttegd]

Make ROBOT fail when the reasoner finds inferred equivalent classes.

As recommended by Chris Mungall (rationale) and Nico Matentzoglu on Slack.

As for the other FlyBase ontologies:

• already done for FBbt with Disallow inferred equivalencies when reasoning. drosophila-anatomy-developmental-ontology#1319
• cannot be done for FBcv, it has to remain on assert-only
• currently cannot be done for DPO, which has one non-asserted equivalence between CL:0000003 (cell) and GO:0005623) (obsolete GO term for cell); that equivalence is brought in by CARO, whose term CARO:0000013 still refers to GO:0005623 even though it has been obsoleted (Remove GO:cell obophenotype/caro#23); if we can get that fixed in CARO, then we should be able to switch the allow_equivalents setting in DPO from all to assert-only.