We now have live (to be executed), failed and to be reported queues.
Archive jobs have all three types, retrieve jobs do not have a to be reported
queue. The RootEntry interface interface now provides the choice between the types.
All uses are currently hardcoded to LiveJobs.

The error(s) gets recorded at failure time, and the list is printed at
job deletion time.

This allows helgrind to be aware of succession of events.
Also reduced the default queue depth for unit tests.

Adapted the in-RPM script generation.

The delay will initially slow down the user and then the semaphore will block.
This prevent the queue from going too big and the agent object from growing
so big all becomes slow.