• (Addition) Add initial implementation for TriG-star parser.
  
• (Addition) Add support for parsing and evaluating SPARQL-star queries.
  
• (Update) Improve implementation, docs, and tests for accessing parsers
  and serializers by file extension.
  
• (Update) Update Turtle, SPARQL-XML, and SPARQL-JSON parsers to support
  RDF-star.
  
• (Update) Update docs and add tests for handling of base URIs in parsers
  (#158).