This will remove contention on the drive register as drives uipdate their statuses.
Also simplified structures in OStoreDB implementation (less references with added friend relations).

Replaced set_target_properties( .. .. INSTALL_RPATH ..) with set_property (TARGET .. APPEND PROPERTY INSTALL_RPATH ..)

In order to be efficient, the data (tape status and queue sizes) is cached in memory.
This function needed access to the catalogue (where the tape status is located).
This in turn required passing the catalogue object to:
 - The garbage colletion functions for all object types.
 - The garbage collector object now keeps a reference to the catalogue.
 - The path to the catalogue credential file should now be passed to cta-objectstore-collect-orphaned-object
 - The OStoreDB also needs a reference to the catalogue in order to queue retrive requests.

 The garbage collection member function are now also being passed a log context, so the requirement for better
 log of object fate can also be fulfilled later. This in turn required the passing of a logger object to
 the object store and relative helper classes.

 Finally, a dummy catalogue class has been created to be used in unit tests.

Created an objectstore utility for requeuing ArchiveRequests after deleting archive or retrieve queues.

This utility is to be used for cleaning up the pre-prod environement following a schema change in the archive queues.
It could support all object types on the long run, but currently only supports ArchiveRequests.

Created an objectstore utility cleaning up the root entry after deleting archive or retrieve queues.

This utility is to be used for cleaning up the pre-prod environement following a schema change in the archive queues.

Factored a first function out of OStoreDB into Herlpers.

Implemented Agent::garbageCollect()
Made AgentWatchdog fetch the timout from the agent object.
Fixed unconditional time tounter reset in AgentWatchdog::checkAlive()
Fixed missing log for garbageCollection.
Added utility (cta-objectstore-unfollow-agent) to mark agents as not followed when they get orphaned. This utility detects looping ownerships (two garbage coolectors watch each other and both die synchronously). This utility is not packaged.
Various log improvements.

Created a garbage collector subprocess for the drive daemon.
Created a AgentHeartbeat thread and added it to frontend, drive subprocess and GC subprocess.
Fixed logs and drive subprocess.
Renamed common/threading/Threading.[hc]pp to Thread.[hc]pp as there is only one class left in this file.

This new package contains the old makeMinimalVFS (renamed to cta-objectstore-initialize)
plus cta-objectstore-list and cta-objectstore-dump-object.

Agent becomes a usual class, like any other in the object store.
Object name generation (agent's and others) is now handled in the separate AgentReference.
The previous situation created race conditions.

Removed deprecated structures from archiveNS and nameserver namespaces. Removed RetrieveToFileRequest.

The values are now hardcoded.
Cleanup:
  - Removed object store unit tests for data now in the catalogue.
  - Removed now unnecessary 2nd step addition of retry limits to archive jobs.
  - Removed deprecated ArchiveToFileRequest files.

Added binned running counters (ValueCoundMap) for managing summaries of priorities in object store queues.
Simplified the interfaces to the getPendingArchiveJobs and getPendingRetrieveJobs functions in Scheduler and SchedulerDB.
Removed now unused ArchiveToTapeCopyRequest.
Removed long unused mockScheduler.
Removed _old_protoype files.

Started morphing the code to accomodate both the move some data structure from OStoreDB to catalogue and shared structures modifications.
Renamed class members using underscode instead of mixed case.
Removed mount criteria from in-memory tape pool representation.
Removed support for path of archive files for in-memory representations.
Removed all but maxDrives allowed from in-memory representation of mount
policy.
Created new constructor for UserIdentity.
Switch the UserIdentity used by RemoteFileStatus.
Renamed TapePoolQueue to ArchiveQueue.
Replaced CreationLog usages with EntryLog.
Renamed TapeQueue to RetrieveQueue.
Removed support for data now gone to catalogue from RootEntry.
Removed corresponding structures from object store.
Removed corresponding calls from SchedulerDatabase and inheriting
classes (OStoreDB).

ObjectOps by adding a second parameter to the template.

Thanks to Steve Murray for findind the solution.

This implied removing tpconfig, tplabel and tpstat.

Partial implementation of per object type dump.

Added rados library version validation and cleanup.
Created a new shared library to ensure instantiation of singleton object supporting the former.
Removed several double creations of drive objects in unit tests.
Added cleanup for potentially unused drive objects in unit tests.

Extracted BackendPopulator and OStoreDBWithAgent from the XrootD plugin to avoid linking the plugin too widely.

Added explicit dependencies for header files and replaced misplaced include to ensure parallel comilation.

Added tolerance to BackendRados::ScopedLock::release() when releasing a deleted object's lock.
Switched back to old style m_radosCtx.objects_begin() for compatibility with older releases of ceph.

Added a list method for the backends so we can clean up the rados store before running each unit test, which expects a fresh store.
Added a new command line tool to list the contents of the backends.