Replace instances of oa:TextualBody with blank nodes

[arnikz]

For example, <http://makingsense.liacs.nl/rdf/nc/textualBody1> in

SFB-Annotator/data/rdf/example_1_1.ttl

Lines 1 to 6 in 375b8c9

	<http://makingsense.liacs.nl/rdf/nc/anno1> a <http://www.w3.org/ns/oa#Annotation>;
	<http://purl.org/dc/terms/creator> <http://orcid.org/0000-0002-2146-4803>;
	<http://purl.org/dc/terms/date> "2017-09-21";
	<http://www.w3.org/1999/02/22-rdf-syntax-ns#value> "1"^^<http://www.w3.org/2001/XMLSchema#int>;
	<http://www.w3.org/ns/oa#hasBody> <http://makingsense.liacs.nl/rdf/nc/taxon1>, <http://makingsense.liacs.nl/rdf/nc/textualBody1>;

SFB-Annotator/data/rdf/example_1_1.ttl

Line 15 in 375b8c9

<http://makingsense.liacs.nl/rdf/nc/textualBody1> a <http://www.w3.org/ns/oa#TextualBody>;

See https://www.w3.org/TR/annotation-vocab/#textualbody.

[lisestork]

I will check the current data model for semantic tag replacement & IIIF

[arnikz]

I will check the current data model for semantic tag replacement & IIIF

This is related to #25 and #26 instead.