* Converted ripcd(8) to use RDApplication.
* Documented a 'Notification' message type in
'docs/apis/notification.xml'.
* Added an 'RDMulticaster' class.
* Added an 'mcast_recv_test' program in 'tests/'.
* Added a 'SYSTEM.NOTIFICATION_ADDRESS' field to the database.
* Incremented the database version to 276.
* Added an 'Mcast Address for Notifications' control to the
'System-Wide Settings' dialog in rdadmin(1).
* Implemented the 'Process Notification' ['ON'] command in
ripcd(8).
* Added an 'RDRipc::sendNotification()' method.
* Added an 'RDRipc::notificationReceived()' signal.
