Add conjugate relations from CHEBI and include transitive versions

[cmungall]

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CHEBI includes a number of relations that are very useful for queries, in particular conjugate base/acid relations

In CHEBI these have no associated logical axioms other than inverse_of (which of course in OWL obtains on the instance level - chebi makes reciprocal assertions)

    <!-- http://purl.obolibrary.org/obo/chebi#is_conjugate_acid_of -->

    <owl:ObjectProperty rdf:about="http://purl.obolibrary.org/obo/chebi#is_conjugate_acid_of">
        <owl:inverseOf rdf:resource="http://purl.obolibrary.org/obo/chebi#is_conjugate_base_of"/>
        <oboInOwl:hasOBONamespace rdf:datatype="http://www.w3.org/2001/XMLSchema#string">chebi_ontology</oboInOwl:hasOBONamespace>
        <oboInOwl:id rdf:datatype="http://www.w3.org/2001/XMLSchema#string">is_conjugate_acid_of</oboInOwl:id>
        <oboInOwl:is_cyclic rdf:datatype="http://www.w3.org/2001/XMLSchema#boolean">true</oboInOwl:is_cyclic>
        <oboInOwl:is_transitive rdf:datatype="http://www.w3.org/2001/XMLSchema#boolean">false</oboInOwl:is_transitive>
        <rdfs:label rdf:datatype="http://www.w3.org/2001/XMLSchema#string">is conjugate acid of</rdfs:label>
    </owl:ObjectProperty>



    <!-- http://purl.obolibrary.org/obo/chebi#is_conjugate_base_of -->

    <owl:ObjectProperty rdf:about="http://purl.obolibrary.org/obo/chebi#is_conjugate_base_of">
        <oboInOwl:hasOBONamespace rdf:datatype="http://www.w3.org/2001/XMLSchema#string">chebi_ontology</oboInOwl:hasOBONamespace>
        <oboInOwl:id rdf:datatype="http://www.w3.org/2001/XMLSchema#string">is_conjugate_base_of</oboInOwl:id>
        <oboInOwl:is_transitive rdf:datatype="http://www.w3.org/2001/XMLSchema#boolean">false</oboInOwl:is_transitive>
        <rdfs:label rdf:datatype="http://www.w3.org/2001/XMLSchema#string">is conjugate base of</rdfs:label>
    </owl:ObjectProperty>

there is no documentation on these in the OWL, but there is a section in the chebi user guide that details their use:

We should coordinate with CHEBI such that there is OWL for these relations that have full documentation

Additionally, these are not transitive in CHEBI - they are used to query the direct conjugate. It would be useful to have transitive versions.