In GAF parsing, warn if inconsistent values for any field

[cmungall]

GAF is a denormalized format so there is necessarily repetition of information

Any such repetition should be consistent. E.g. info about a gene product is repeated (symbol, description, synonyms).

Any violation should be added to the report

See my comment here: https://github.com/geneontology/helpdesk/issues/139#issuecomment-401950612