Changed design to use events detectors instead of predicate scheduler.

src/design/measurements-generation-class-diagram.puml

...timation/measurements/generation/EventBasedScheduler.java

...kit/estimation/measurements/generation/GroundAtNight.java

...timation/measurements/generation/SchedulingPredicate.java

...ekit/estimation/measurements/generation/SignSemantic.java

...org/orekit/estimation/measurements/generation/Sunlit.java

...estimation/measurements/generation/VisibleFromGround.java