Basically allow users onwiki to create custom types of notifications and send them. Right now they can only be sent via software actions that call EchoEvent::create and register various hooks.
Usecase: sane notifications for XfD, your file needs categories!, comment on this RfC please, etc.
Need some kind of structure for each notification: notification text, email template, image? category, priority, etc.
A special page which lets a user send out notifications, based on the types that are already set up.