Vava pv checker improvements
Adds functionality to plot PV efficiencies and resolutions vs. the multiplicity and z position
Adds functionality to plot fake rate vs. reconstructed PV multiplicity, for now does not work because the weights for all the tracks in the beamlinePV finder are being set to 1 so that all tracks appear to contribute equally to all PVs.
Clean up use of obsolete n_tracks member of the PV::Vertex class (nTracks exists as a member and performs the same function)
Edited by Florian Reiss