Improve FTimerManager timers accuracy #7
Description
The FTimerManager had a couple of limitations due to the way it was designed.
Mainly, the length (DeltaTime) of the current frame was never accounted for in timers when starting them, meaning that an overly long frame (in terms of DeltaTime) would make no difference to a timer over an extremely short one, and that is "wrong", at least in some cases.