Add setting for configuring output of PGUN simulation (@adavis)
See merge request !2385 (merged) (cherry picked from commit a95d551b)
Needed to propagate pGun PV from Gauss through the Boole processing step for Run2 pGun productions with Gauss v54r0 (Sim10) and Gauss v49r16 (Sim09) or later. To be activated for steps that process pGun, by setting SimConf().pGun=True
Edited by Marco Cattaneo