Synch changes from Turtle/N-Triples/N-Quads

[gkellogg]

Basically, do what is done in w3c/rdf-turtle#107 to TriG.

• Use style for table cell text alignment rather than inline-css and change how whitespace is introduced between --.
• Add SHOULD criteria on IRIREF for RFC3986 section 3.3.
• Change RDF12-CONCEPTS#dfn-literal to RDF12-CONCEPTS#dfn-rdf-literal, which is the correct term to reference.
• Changes to synchronize with N-Triples.

Also from w3c/rdf-n-quads#80

• Add link to supporting tests for normative C14N UCHAR language.
• Add language to require that only valid IRIs, language tags, and base directions be used to form triples, otherwise signaling an error. Fixes Update common files. rdf-n-quads#37.
• Narrow IRI validity requirements
• Suggestions from @afs on weakening language on parser behavior in the presence of ill-formed terms.
• Add note on processors producing errors and the potential affect on the result.
• Fix dfn-literal. add "period" before full-stop character, other misc.
• RFC3986 conformance.
• Style updates from Turtle.
• Add test links for negative syntax IRI and LANG_DiR tests.

[domel]

@gkellogg I created a draft PR #49. Your help is appreciated.