Determinstic comparisons of Particle in RelationsTables

Base comparison of Partilces in Relations tables not on pointer values, but on their key and the identifier of the container they are part of. The latter requires that container to have a valid registry (i.e. normally in must be in the event store, unless some additional work is done -- as in eg. Rec!3343 (merged))

Requires Rec!3343 (merged) (to avoid a SEGV) Sits on top of !3998 (merged) (which does the same for ProtoParticle)