Add support for homonyms to taxonomic thesauri

[ljwalker]

Discussion started per recent request from SEINet user:

Symbiota's taxonomic thesaurus does not support homonyms, e.g. taxon records where the genus and species values are the same, such as in Lophogyne capillacea (Tul.) C.T.Philbrick & C.P.Bove and Lophogyne capillacea Pulle.

If homonym support interests you, please add your thoughts to this thread!

[ljwalker]

Lack of support for homonyms was also noted as a challenge for https://biodiversidad.gt/portal by @ksorellana:

Orellana KS et al. (2022) Taxonomic Curation in a Multi-taxa Symbiota Portal. Biodiversity Information Science and Standards 6: e93671. https://doi.org/10.3897/biss.6.93671