New FActorRange, TActorRange and FSelectedActorRange.
Some example usage of the new range types.
FNetRelevantActorIterator removed, as it's not used.
FTickableLevelFilter removed.
Actor iterators' operator bool made explicit.
#codereview robert.manuszewski
[CL 2553370 by Steve Robb in Main branch]
#proj core
#branch UE4
#summary Moved global variables to statics in FApp. Removed unused GUnclampedDeltaTime.
#codereview robert.manuszewski
[CL 2043034 by Mikolaj Sieluzycki in Main branch]