Port remaining ChEBI relations to RO

[cthoyt]

Following #643, there are a few relations from ChEBI that would benefit from inclusion in RO (also as part of a more general effort to get rid of hash relations across the OBO ecosystem):

• has functional parent
• has parent hydride
• is enantiomer of
• is substituent group of
• is tautomer of

These are described in this internal Google doc for ChEBI annotators, but some of the descriptions are pretty difficult to decipher

[wdduncan]

@cthoyt I don't know that much about functional groups and molecular graphs, so I am not qualified to review these relations. Is there someone you would like to review them?

I noticed that definitions include the word obo:has_part. Can you just say has part? Does using obo:has_part have special significance?

[cthoyt]

I hate to put more on his plate, but Chris Mungall is a good candidate. @bvarner-ebi was active in the last discussion and as always input from the chebi side from @amalik01 is valuable

Note that the document I linked is from ChEBI - I can't speak for why things are written the way they are nor can change them. On the PR, I tried to rewrite these definitions to be more approachable.