Check and fix for negative bins + some templates
Implemented a method to check and fix for negative bins, setting them to 0. Also, the other fixes are simplified.
Set the title of the TEfficiency objects, to better understand where there are problems when computing the signal yield.
Two almost identical methods for TH2D and TH3D are now templated, to avoid repetition.
The description of some errors of effLUT are now more detailed.