Add option to use powhegLHEReader for Herwig7 in Herwig72ConfigLHEF.py
Added an option to Herwig7Config.lhef_powhegbox_commands(..) to use a special LHEReader to Herwig7, which is able to propagate multiple event weights. The actual reader has to be delivered via a gridpack.
This is urgently needed for a new Powheg+Herwig7 W sample
Tagging @ewelina