Fix scope name in symbol list settings

Still contained the old one
Make use of new zeroIndentPattern and disable indention of directives and SPARQL prefixes
[command] Introduce syntax validation command

Actually just munges Rapper output -- but it looks much nicer
[autocomplete] Make all parts of extractor stylesheet be aware of different IRI notations

Now also algorithm for type-attribute
[autocomplete] Local prefix declarations should have precedence over those from prefix.cc

The current document is now scanned for the according @prefix directive
and when found its IRI is used to lookup everything else. When no
matching @prefix directive is found, Turtle bundle falls back to
prefix.cc (old default behaviour).
Update README to cover syntax validation feature and new prefix resolving scheme