Schedule nodes may have a maxPlaysPerHour field on them which should be used during the schedule assessment routine which decides whether to include a schedule or not.

Players should keep an in-memory count of the number of plays for a schedule in the current hour, and if that exceeds the maxPlaysPerHour that schedule should be removed from the list. A setting of 0 means "never remove".

See: xibosignage/xibo#2898