Function ontology_q42_bytes 

pub fn ontology_q42_bytes(
    concepts: &[OntologyConcept],
    hier: &Bp3dHierarchy,
    isa: &HashMap<String, String>,
) -> (Vec<u8>, usize)

Serialise the ontology of concepts into unified v3 .q42 bytes (object-sorted blocks). Returns the bytes and the number of quins in the graph.