RDF/XML Fini, and Python - slide "Collections"

New vocabulary (one class, two properties, and an individual):
- rdf:List
- rdf:first
- rdf:rest
- rdf:nil
These are intended to represent closed lists, recursively defined (specifically modeled on cons cells)

There is special syntactic support for them:

<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
         xmlns:ex="http://example.org/stuff/1.0/#"
	 xml:base="http://example.org/stuff/1.0/">
<rdf:Description rdf:ID="Bijan">
	<ex:siblings rdf:parseType="Collection">
		<rdf:Description rdf:ID="Sam"/>
		<rdf:Description rdf:ID="Mark"/>
	</ex:siblings>
</rdf:Description>
</rdf:RDF>