As part of the efforts of the combined PID subgroup we are continuing to develop...

As part of the efforts of the combined PID subgroup we are continuing to develop to the extent
it is possible ESD/AOD "neutral" classes using AliVTrack and pushing detectors to provide
code for the AliPIDResponse class.

This update introduces also a new class AliPIDCombined which uses AliPIDResponse interfaces to obtain
PID probabilities and then computes Bayesian probabilities within the framework discussed in the sub-group.
Note the updated .pkg and STEERBaseLinkDef.h

Pietro Antonioli <Pietro.Antonioli@bo.infn.it>