fix: inputs/NY/validations.sql, schemas/vegbien.sql: _specimens_13_count_of_all_verbatim_and_decimal_lat_long: count lat/longs together instead of separately, because the DISTINCT is by coordinate pair, not individual coordinate value (which wouldn't make much sense)

bugfix: schemas/vegbien.sql: rm_output_queries(): need to account for the fact that util.truncated_prefixed_name_regexp() returns a whole-string regexp. this drops support for removing output queries with a particular group prefix, which we no longer use.

bugfix: schemas/vegbien.sql: rm_output_queries(): need to include relations whose names were truncated, as well

fix: schemas/vegbien.sql: public_validations schema comment: to remove a validations query so its columns can be changed: use rm_output_queries() rather than rm_query_view() because that also removes input queries

bugfix: schemas/util.sql: is_castable(): need to pass NULL through, for proper NULL propagation

fix: inputs/NY/validations.sql: _specimens_13_count_of_all_verbatim_and_decimal_lat_long: use new is_castable(), which is much more accurate than Brad's custom regexp for determining if something is numeric

inputs/NY/validations.-.util.sql: added util.is_castable() wrapper

schemas/util.sql: added is_castable()

schemas/util.sql: added try_cast()

schemas/util.sql: added util.cast(), which allows casting to an arbitrary type without eval()