add reconstructed pid

2 Options are added: pid_mode = 2: reconstructed pid with max. purity & purity > requested purity pid_mode = 3: reconstructed pid with purity > requested purity, pid-specific purities are optional Required input is output from pid-framework (analysistree with "RecTracks") There is no need to change main2.cpp to run pid_mode 0 & 1 -> additional commented lines are just examples to run with pid_mode 2 & 3.