fixed the retrieval of OPTIONAL results from expansion tree.  Simplified SPARQLNode.returnResult..
fixed the retrieval of OPTIONAL results from expansion tree.  Simplified SPARQLNode.returnResult..

ssssam/rdflib,marma/rdflib,dbs/rdflib,dbs/rdflib,RDFLib/rdflib,RDFLib/rdflib,RDFLib/rdflib,marma/rdflib,armandobs14/rdflib,avorio/rdflib,ssssam/rdflib,yingerj/rdflib,dbs/rdflib,ssssam/rdflib,armandobs14/rdflib,ssssam/rdflib,yingerj/rdflib,RDFLib/rdflib,marma/rdflib,armandobs14/rdflib,armandobs14/rdflib,yingerj/rdflib,avorio/rdflib,dbs/rdflib,avorio/rdflib,yingerj/rdflib,marma/rdflib,avorio/rdflib