Add SimulateCavern simFlag, which can be used independently of CavernBG and cosmics simulation

As reported in ATLASSIM-4216, for radiation studies it is useful to be able to include the ATLAS Cavern in simulations without making the other configuration tweaks associated with Cosmic-ray and Cavern Background simulation. This merge request adds a SimulateCavern simFlag which is set when running Cosmic-ray and Cavern Background simulation jobs, but can also be set separately to allow the cavern to be included in simulations with no other changes.

Simulation/G4Atlas/G4AtlasApps/python/atlas_flags.py

-# Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+# Copyright (C) 2002-2019 CERN for the benefit of the ATLAS collaboration
 
 """
 SimFlags specific to the full ATLAS simulation
@@ -182,6 +182,15 @@ class VertexTimeOffset(JobProperty):
     StoredValue = False
 
 
+class SimulateCavern(JobProperty):
+    """
+    Turns on the simulation of the ATLAS Cavern
+    """
+    statusOn = True
+    allowedTypes = ['bool']
+    StoredValue = False
+
+
 class CavernBG(JobProperty):
     """
     Flag to turn on the simulation of cavern background (and all that goes with it)