Get ISF configuration to run a test without failing.
Many changes of private tools to public tools.
Add flag-based default decision for ConfigFlags.Sim.ISF.HITSMergingRequired (cc @jchapman )
Add Kernel_ATLFASTIIMTCfg
Get BaseSimulationSelector to accept an empty simulator, as needed for MT.
Numerous changes and suggestions are thanks to @bleban