Improve aa regression test results when XOTcl is loaded (add warn_p to doc API); Provide default values from function args, when provided (it improves API documentation and fixes a bug in e.g. acs_attribute__create_attribute(), which does not provide a default value for 'storage' as documented, when NULL is provided; Resolve cyclic dependencies for ::xo::db::Attribute; Use column_name for attribute creation.