I couldn't figure out what the original code was intended to do, but
I've tried to fix the problem without changing it more than necessary.

Closes #6428

…rison

It never took off, and I very much prefer communicating through the forum
and bug tracker.

… properties

Closes #6436

* Do not treat the opening '<' of an expanded IRI atom as an operator

The existing code would not highlight the IRI atom "<foo#bar>" in the following line as an atom.
FILTER( ?x = "42"^^<foo#bar> )
for example everything after the # would be highlighted as a comment. This is because the sequence "^^<" while all "operator characters", are not all SPARQL operators in this case: the "<" introduces the IRI atom. I special-case the "^^".

* Improve PN_LOCAL parsing to SPARQL 1.1

The following legal sequences of characters from SPARQL 1.1 are additionally parsed as being the right-hand-side of a prefixed IRI.
1) Colons
2) PERCENT escaping
3) PN_LOCAL_ESCAPE escaping

Closes #6442