Reconciliation Queries: consider renaming `v` and `pid` properties

[Abbe98]

The current properties v and pid aren't very descriptive and their names do not indicate their relationship. I would therefore propose that these are renamed to: propertyValue and propertyIdentifier.

[fsteeg]

Yes, those are quite cryptic indeed. We discussed the propertyIdentifier naming in today's meeting and were wondering if maybe propertyId would be more consistent with our use of id fields in other objects. On the other hand, propertyIdentifier seems very consistent with the matchQuantifier and matchQualifier wording.

[Abbe98]

I have no strong opinions at all here, I just picked the suggestions from similarly named properties. :-)

[saumier]

Following the discussion at the monthly meeting in June, I will open a PR with changes to the spec using propertyValue and propertyId.