Rename stupid variables from a,b,c,d to more useful names
Remove getTauDaughters dependency to fix seg faults.

getChargedObject no longer relies on getTauDaughters. This is a good thing
since the latter seg faulted when pythia takes care of tau decays instead
of calchep. (calchep does e.g. tau -> udbar -> pi, pythia does tau ->pi)
This confused getTauDaughters. Instead, getChargedObject is more general
and just loops through generations of tau children until it hit the one
stable charged object, like the pythia hadronisation code does.