using 2m as Nf treshold

reverting to commit 7999, before CMW option was introduced

using b and c mass as tresholds for Nf in the cmw prescription

Using variable Nf for CMW prescription in Matchbox Powheg

modification necessary to run qcd 2->2 processes

fixes in qtildeshowerhandler

first attempt of showering the timelike child from ISR

restoring minbias modifications and 2019 copyright