Move geometry.Boundary back to primitive package as in ISO 19107:2003

The primitive package holds all the atomic geometries plus all the types needed to satisfy their boundary operations apart from the single interface complex.Complex. (Presumably the semantic mismatch of placing that single interface in the primitive package was too much.) Having the Boundary interface floating all alone in .geometry. doesn't make much sense. It's a subclass of .complex.Complex but all its sub-classes are in the primitive package.

I would like the interface moved back into primitive.