This includes :
  - merge of d2dtransfer into diskmanagerd
  - drop of the WAITDISKTODISKCOPY state in DiskCopy, and of the diskcopies for ongoing replication in general. Now DiskCopies are only created at the end of the replication, when they actually exist on disk
  - drop of the StageReplicaRequest table and concept
  - introduction of the DiskToDiskCopyJob table, holding the list of ongoing disk to disk copies
  - a split of transferToSchedule into userTransferToSchedule and D2dTransferToSchedule
  - an according split in the dispatcher part of the transfer manager to call both methods. Note that with this commit, both methods fill the same FIFO queue of transfers and both take everything they can find without any throttling.

At this stage, the draining facility is broken.