Added SPARQL JSON parser.
Added SPARQL TSV parser and serializer.
Added Attean::API::ResultOrTerm role.
Added Attean::API::ResultOrTerm role.
Added Attean::API::TermIterator role.
Added Attean::API::ResultOrTermParser role.
Added Attean::Algebra::Ask class.
Code cleanup.
Improved coverage of SPARQL function library.
Added Attean::Literal numeric constructors: decimal, float, and double.
Improved coverage in Attean::SimpleQueryEvaluator.
Added parse_term_from_string method to Turtle and N-Triples parsers.
Added boolean parsing support to SPARQL XML parser.