One base class should be implemented that makes the basic handling to establish DICOM image source relations.
Idea is that one just needs to derive from this new class and just adds the purpose information etc. that are needed to distinct different source relations.
IMPORTANT: All DICOM relation entries that differ per slice and timepoint (e.g. the referenced instance UID or SOP class UID) are stored under the same key but in a SpatioTemporalProperty. Background/Reason: This only happend with images due to the MITK image volume vs DICOM staple discrepancy. If we write it into DICOM each slice will have its own IOD and thus there is no conflict in tag transfer. Each slice will get its specific value out of the property.