Implementing counters in ClassifyPhotonElectronAlg
Implementation of counters in the algorithm ClassifyPhotonElectron. Counters are obtained on a (end-start) basis. Energy counters and X, Y position counters are consistent with the ones implemented in the tool. There are insignificant differences. 'Z' counter differs because the tool uses a different starting point (taking into account the incident angle). I added two counters (for photons and electrons) that count the number of rejected hypos due to the pt cut. All the new counters amount to the same numbers in single- and multi-threaded tests. This MR supersseds !1966 (closed).
Reference updates in Brunel!1000 (merged) Moore!464 (merged)