sql.py: Added function_param0_type()

sql.py: parse_exception(): function MissingCastException: Only treat DoesNotExistException as a MissingCastException if the query that was run did not already include a cast, to avoid infinite exception-handling recursion

sql.py: parse_exception(): function MissingCastException: Fixed bug where determining whether the exception is a MissingCastException rather than a DoesNotExistException needs to check whether the function exists rather than whether it's the same in the exception message as in the query that was run. The exception message will of course copy the function name verbatim from the query, so there is no information in the exception message itself to indicate whether the DoesNotExistException was caused by a missing cast or by a nonexistent function.

sql.py: parse_exception(): function MissingCastException: Documented that the regexp match to extract the function name also checks that a function signature with param types was matched, indicating a function call rather than cast to regproc. This check will also help avoid infinite recursion when function MissingCastException parsing calls database structure introspection functions.

sql.py: parse_exception(): function MissingCastException: Don't match quotes around the function name because this particular exception (incorrect param type) does not include them. Casts to regproc, which also produce a DoesNotExistException, include the quotes but do not indicate a MissingCastException.

sql.py: parse_exception(): function MissingCastException: Fixed bug where the 1st param's type in the exception's function signature is not actually the type the argument needs to have, because this is just the argument's current type

sql.py: parse_exception(): typed_name_re: Also match identifiers without quotes, such as functions in "No function matches the given name and argument types" errors. This fixes a bug where DoesNotExistExceptions could not be parsed as MissingCastExceptions when applicable because the DoesNotExistException pattern would not even match.

inputs/.NCBI/: Renamed higher_taxa to nodes because it currently doesn't just contain the higher taxa

schemas/vegbien.sql: taxonlabel: taxonlabel_2_set_canon_label_id(): Only run if matched_label_id has actually changed, to avoid infinite recursion when updating canon_label_id on labels that resolve to this label when there are cycles in the data

inputs/.NCBI/: Renamed higher_taxa to nodes because it currently doesn't just contain the higher taxa