Import CHEBI terms into MOP and RXNO editor files via a seperatly maintained module

[StroemPhi]

For a better maintainability the editor files for both ontologies (mop-edit.owl and rxno-edit.owl) should each have their own CHEBI import module. These CHEBI import modules would have to be maintained in the repo as well. As proposed in #40 this is best done with the ODK workflow.