inputs/.TNRS/schema.sql: MatchedTaxon, etc.: added accepted_morphospecies_binomial derived field

bugfix: schemas/util.sql: restore_views(): need to specify view name for a manual existence check, in case the view definition becomes invalid, which would produce a nonstandard (uncatchable) exception

bugfix: schemas/util.sql: explain(): don't display any log messages printed by IMMUTABLE functions in the query, which EXPLAIN apparently runs

schemas/util.sql: create_if_not_exists(): added relation param, which can be used to ensure that a standard exception is always generated if the relation exists, even if the table definition would be invalid (which generates a variety of exceptions)

/README.TXT: to back up the vegbiendev databases: added step to review diff before performing backup, in case the backup scripts break and try to synchronize things incorrectly

bugfix: schemas/util.sql: try_cast(), is_castable(): also need to handle syntax_error_or_access_rule_violation, which is thrown by ::regclass

schemas/util.sql: added relation_exists()

schemas/util.sql: save_drop_views()/restore_views(): store the view path in addition to the definition so it can be used in restoring

bugfix: schemas/util.sql: in_reverse(): can't use `SELECT *` for composite types because this expands them

bugfix: schemas/util.sql: array_reverse(): can't use `SELECT *` for composite types because this expands them