postgres/v0.4.0

Changed

• Breaking: requires github.com/standards-lab/go-database v0.7.0, whose
  ErrConnectionFailed is sqlate's sentinel.
• New checks the config with database.Config.Finalized, so a config missing any field the
  base reads panics as the base's New does; it checked only ConnTimeout before.

Fixed

• A Host that is a Unix-socket directory (starting with /) failed to parse, because New
  joined it into the URL's authority. New now passes it, with the port, in the URL's query.