Allow entities to upgrade into other entities.
This new components allows giving the upgrade a cost, required technologies, and a required time.
Implement gates using this generic component.
(There are no real entities.)
This creates an object that contains a GuiInterface TimeNotification that is not used (perhaps it should be used instead of doing the performance improvmeent and not constructing it.)
Not sure where we need if for, but it is possible since rP19869.