Also use string or port in nquads parser

Julien LepillerFri Oct 09 00:19:45+0200 2020

3c31417

guile-rdf/tests
namelast commitdate
nquads.scm.inSwitch tests to srfi-64Wed Oct 07 01:14:41+0200 2020
semantics.scm.inSwitch tests to srfi-64Wed Oct 07 01:14:41+0200 2020
turtle.scm.inSwitch tests to srfi-64Wed Oct 07 01:14:41+0200 2020