CompoundLocation RDFization

I have implemented a preliminary -- possibly incomplete -- RDFization of CompoundLocation objects.

@peterjc Please have a look at the use of rdfs:member. I recall there was a discussion about swapping a FALDO doman/range restriction, which might apply here, but I cannot find that discussion anymore.

If RDFized like I implemented it, it is currently not clear to me how I arrange the FeatureLocation objects in a list.