Runtime worker : unblock the last waiting job and prevent any new job to wait when Main Worker is being shut down.

Add some "pipe to self" trick in Pyro server to accelerate runtime shutdown instead of waiting for arbitrary pyro timeout.

If call to GetPLCstatus can't be executed in PLC, then obtained status is disconnected. Status on "None" is not relevant anymore, and is replaced by Disconnected.

Enure that all threads are joined before trying to exit