Added the basis of result grouping (still need to refactor)
Reduced dependencies, improved result transformer
ResultGrouping: Test is green, but code still needs to be refactored.
Added unit tests and some fixes, javadocs
Modified to excluded null identity values
Extended javadoc
No longer copying last invoked selection path.
Added check in case property path is not collection-compatible
Merge pull request #22 from gert-wijns/ResultGrouping

Result grouping