Include SPARQL parser

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Still being a great library RDF::Query turned out to be too buggy for just parsing, inspecting, and pretty-printing SPARQL queries. It might be better to create a SPARQL parser with Marpa::R2 or Regexp::Grammars based on the official SPARQL grammar. This could also solve #11.

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A SPARQL parser is too heavy, RDF::Query or https://metacpan.org/pod/AtteanX::Parser::SPARQL should do the job with https://metacpan.org/pod/AtteanX::Serializer::SPARQL