Need a _deduplicate function

(User Story, Checked In , Priority: Critical, Test Status: Unit tested , Reported By Bad Link: Thing 3y284oe not found, )

Data Model

Summary: Eric has a use case involving _withValueIn(), where he is feeding in a collection with a lot of duplicates, and is winding up with an enormous, unmanageable number of duplicates. I think the behavior is technically correct, but he doesn't have a way to produce workable results.

This could be addressed by having a simple _deduplicate function, which takes a QList and returns a proper QSet, removing all duplicates along the way.