Please not that DriveCatalogue.cpp still needs to be modified to
actually implement to idempotent behaviour.

Optimized selection of files to migrate by introducing a kind of ordering by time : we take the oldest candidates (10K by default), then group them by periods and within the oldest period, we use filesystem availability.

Improved error reporting in listtransfer : when a manager is not available, listtranfer -p will specify it on top of returning '-' in the NBUTPEND column. Note that this changes the listtransfer protocol

DebugMountSessionForVdqmProtocol is a temporary class that will eventually
be replaced by the offical MountSession class.  The purpose of the
temporary class is to field test our undestanding of the vdqm protocol.

Added a submissionTime in the transfer and used it to determine if a job has to be timed out while pending in the diskmanager.
Made internal (non USER) disk-to-disk transfers have no pending timeout.

Please note that this commit only adds the prototype/specification for
Vdqm::mountTape().  The method's implementation has been left empty.

Please note that the current code emulates a tape mount session.  The
goal is to test our understanding of the vdqm protocol, so that when
the official tape mount session code is ready it will hopefully not
have to debug the vdqm protocol.

In order to facilitate debugging with gdb, only mask Ctrl-C whilst
running in the background.  The gdb debugger has its own SIGINT
handler to pause the process anywhere.

Fix for sr #142826: ORA-02292: integrity constraint (CASTOR_STAGER.FK_DISK2DISKCOPYJOB_SRCDCID) violated

Better fix of bug #104192: ORA-02292: integrity constraint (CASTOR_STAGER.FK_DRAININGERRORS_DC) violated - child record found