Force models events detected twice when calling NumericalPropagator.propagator(start, target)

When propagation is called on a time range (start, target) in an integration-based propagator, a first propagation is performed from initial start without user-defined events detection, then user-defined events detectors and step handlers are activated and the second part of the propagation from start to target is performed.

Events handlers from force models however are necessary throughout and properly activated even in the first propagation.

The detectors from the force models are added twice to the integrator : once before starting the first propagation and once before starting the second propagation. This results in events being detected twice and handlers being called twice.