_groupBy should work on the results of _search

(Bug, Closed -> Fixed, Priority: Critical, Test Status: Unit tested , Reported By Bad Link: Thing 3y284oe not found, )
Functions
Summary: This appears not to work, apparently because _groupBy only accepts Things. It should accept PropertyBundles.
Pointed out by Eric.
The hard part here is that the _groupElements property would need to become WrappedValueType, and that might require enhancements to WrappedValueType.