[testcases] some PropertyPaths test cases...

To continue proposing some testcases... some more for propertyPaths attached...
(again, these are not yet tested with any implementation)

... I got to some question collecting those:

"A zero occurrence of a path element always matches."
"A path of length zero connects a graph node to itself."

I understand that these together imply that any pattern ?S PE ?S containing a 
possible zero-length path expression PE always match any node (uri or bnode)
in the graph, right? this assumption is reflected in the zeroDegrees* testcases below.

 - rdfs: 
   query: rdfs.sparql 
   data: TBD ... I guess some common foaf-file would produce some reasonable results... 
   result: TBD
   Description: Query encoding a good part of RDFS reasoning, extending the proposed in Section 5.2 of the current
   PropertyPaths doc.

 - sixDegrees: 
   query: sixDegrees.sparql 
   data: sixDegrees.ttl  
   result: sixDegrees.result
   Description: Construct query returning connections for all people separated by 1-6 degrees of foaf:knows in both directions.

 - sixDegreesUnidirectional: 
   query: sixDegreesUnidirectional.sparql 
   data:  sixDegrees.ttl  
   result: sixDegreesUnidirectional.result
   Description: Construct query returning connections for all people separated by 1-6 degrees of foaf:knows in both directions.

 - zeroDegrees:
   query: zeroDegrees.sparql 
   data:  sixDegrees.ttl  
   result: zeroDegrees.result
   Description: Construct query returning 0-ary connections.

 - zeroDegrees_b:
   query: zeroDegrees_b.sparql 
   data:  sixDegrees.ttl  
   result: zeroDegrees.result
   Description: Construct query returning 0-ary connections, variant of zeroDegrees.

 - zeroDegrees:
   query: zeroDegrees_b.sparql 
   data:  sixDegrees.ttl  
   result: zeroDegrees.result
   Description: Construct query returning 0-ary connections zeroDegrees.