gmap_view supports persisting/freezing fragments but not the authoritative element. It can be convenient to persist the authoritative element as well. For instance, if a ghost map is used to represent some resource connected to a physical heap. Then, after a potential crash, the "old" physical heap will never be changed again, and it can be convenient to persist the authoritative element to obtain persistent knowledge of the state of the resource prior to the crash.
This MR changes gmap_view such that the authoritative element is parameterized by a dfrac instead of a Qp, to support persisting the authoritative state. This change is trivial as the view camera already supports persisting the authoritative element.