KERML_ — Transitivity missing for some time/space associations

Documentation for Within, WithinBoth, and SpaceSliceOf in the specification and libraries say they're transitive, but this isn't formalized in the libraries (might be others), as it is for some other time/space associations.

Add transitivity for time/space relations where it is missing

Other time/space associations missing transitivity are PortionOf, TimeSliceOf, and SpaceShotOf. Transitivity is already modeled for associations HappensBefore, HappensDuring, and InsideOf. The following are transitive, but it is unnecessary to model it:

• Association SnapshotOf, as long as TimeSliceOf transitivity is added, SnapshotOf will be also, due to sufficiency of its cross feature snapShotOf and specializing TimeSliceOf.
• Feature Occurrence::spaceTimeEnclosedPoints, because it has no other portions besides itself and is reflexive, it (indirectly) specializes timeSlices, see self.

Occurrences.kerml, within Occurrence, is revised to model transitivity for associations Within, WithinBoth, HappensWhile, SpaceSliceOf, SpaceShotOf, PortionOf and TimeSliceOf via their cross features spaceTimeEnclosedOccurrences, spaceTimeCoincidentOccurrences, timeCoincidentOccurrences, spaceSliceOf, spaceShotOf, portionOf and timeSliceOf, respectively, similarly to how it is currently modeled in successors, timeEnclosedOccurrences, and spaceEnclosedOccurrences (cross features of associations HappensBefore, HappensDuring, and InsideOf, respectively).

Occurrence::spaceEnclosedOccurrences is also revised to ensure occurrences inside another are outside occurrences that are outside the other.