egamma ART updates
A test is added to run on DRAW_EGZ. This could allow to spot issues not existing in MC (e.g. bad effect on timing cut for topo building on egamma energy linearity) The dcube ref will be updated a bit later.
This MR also adds histograms of the truth origin of reco. photons and electrons, to spot issues in case the MC truth classifier is updated
ping @bistapf
Edited by Jean-Baptiste De Vivie De Regie