Relating COB 'molecular entity' to CHEBI

[nataled]

ChEBI molecular entity: Any constitutionally or isotopically distinct atom, molecule, ion, ion pair, radical, radical ion, complex, conformer etc., identifiable as a separately distinguishable entity.
COB molecular entity: A material entity that consists of two or more atoms that are all connected via covalent bonds such that any atom can be transitively connected with any other atom.
ChEBI molecule: Any polyatomic entity that is an electrically neutral entity consisting of more than one atom. (NOTE from DN: molecule is_a polyatomic entity is_a molecular entity)

During day 1 of COB workshop 2020, the relation mapping between the two 'molecular entity' terms was changed from owl:equivalentClass to skos:closeMatch. This is partway there, but probably not the best mapping since the CHEBI term includes COB atom, complex of molecular entities, and molecular entity. I believe the better mapping would be skos:closeMatch to CHEBI's 'molecule' (where the only difference pertains to charge).