MyTools.hh: added two functions getRelDifference(vec<TH2D*>,etc) and getRelDifference(vec<const TH2D*>,etc)
MyTools.cc: added two functions getRelDifference(vec<TH2D*>,etc) and getRelDifference(vec<const TH2D*>,etc). getRelDifference(TH2D*,newName,etc) calls getRelDifference(vec<const TH2D*>)
Incldue/HistoPair.hh added a function getRelDifference(vec<HistoPair2D*>,etc)
YieldsAndBackgrounds/calc_escaleDiffSyst.C added a check against NO_SYST calculation