EDIT

ref #8871, ref #7980 handle aggregation source mode TAXON for toParent

ref #8871, ref #7980 handle aggregation source modes for SDD aggregation

ref #8871, ref #7980 adapt available source modes for DDS aggregation

ref #8871 try to fix failing aggregation tests (cont.)

cleanup

ref #8871 try to fix failing aggregation tests

ref #8871, ref #9331 fix DescriptionElementSource.clone , e.g. for DistributionAggregation

cleanup

cleanup and minor

ref #7980 delete not needed descriptions after aggregation