Update for RDFLib 4.1.1
    
    Adds RDF 1.1 feature support, RDFa, Microdata, and TriG parsers, HTML5
    handling.
    
    The tools originally provided by python-rdfextras are now provided as part of
    python-rdflib itself, so we add an Obsoletes line accordingly.
    
    We also make SPARQLWrapper an "extras_require" for 4.1; per upstream discussion,
    SPARQLWrapper can be an optional dependency for 4.1 but will be made mandatory
    for 4.2. This gives us time to ensure SPARQLWrapper is packaged while providing
    all of the rest of the bug fixes and additional functionality in RDFLib 4.1.
    
    Signed-off-by: Dan Scott <dan@coffeecode.net>