Support PFlow jet seeds in tauRec
We want to enable the use of PFlow jet seeds in tau reconstruction. A function is implemented in tauRecTools/Root/HelperFunctions.cxx which takes the jet constituent vector and retrieves the appropriate cluster, which requires a different method for topo and PFlow based jets.
The flag is set to use the standard AntiKt4LCTopoJets, so this merge will not change the seed yet.
This merge is in relation to the JIRA ticket here: https://its.cern.ch/jira/browse/ATLTAU-1691