Add option where waitlisted players could not add themselves to an event or be auto registered

Please add an option, event-specific, where you could allow a waitlist, but you could turn off both the "auto-register from waitlist" as well as the option for the player to register themselves if they see a spot open (and that no one else could register if there is a waitlist).  We would like this to be able to control who gets added in a case where we want to have people register as teams so we need to ensure both partners register to complete teams before a new person is added.