Decode line into an RDF N-Triple.
RDF N-Triple (data model).
https://en.wikipedia.org/wiki/Resource_Description_Framework
https://en.wikipedia.org/wiki/Turtle_(syntax) https://en.wikipedia.org/wiki/N-Triples#N-Quads
https://www.ida.liu.se/~robke04/include/publications.shtml
TODO decode subject and object (in Db.exprURI) only when their types are IRIs?
RDF-data model and algorithsm.
Currently supports N-Triples (.nt).
Planned support for RDF Turtle (.ttl) statements (either single-line or multi-line).
TODO can we make inout operator only on the members of the returned NTriple in parseNTriple? TODO parse Turtle .ttl-files (https://en.wikipedia.org/wiki/Turtle_(syntax)) TODO parse N-Quads for use in Wikidata TODO parse RDF/XML