The MySQL authenticator now injects the service user into the list of
allowed users if loading of database users fails. This allows the removal
of common code in the binlogrouter and maxinfo modules.
The MySQLAuth authenticator can now store the cached credentials in a
custom location. This is intended for the binlogrouter, which currently
uses a different location for the user cache.
The MySQL authentication modules now have their own document in the
Authenticators directory. Right now this document only describes the
general details of the MySQL authentication and the new option.