Forward uid to t3lib_BEfunc::getProcessedValue on creating differences
The behaviour to show differences of records basically was copied from the history service.
Since the history only works on differences/deltas and not on fully stored records, no valid uid can be used.
However in the workspaces context each side (live version and workspace version) has a valid uid.
By forwarding this information to t3lib_BEfunc::getProcessedValue hooks can use this valuable data.