1) Simplified the bit in parse_datatype()
2) Made sure it was covered by the test (the "public.year" bit)
2a) ...the rest of changes in the test are to fix incorrect variable
names: c_name/c_lat/c_lng were copy-pasted from a previous test.
3) Removed the branch from parse_pg_cast, which duplicated what
parse_data_type already handled (added in the same commit even
2007995938 )