Include/HistoPair.hh added a method randomizeWithinErr, and a function printHisto(HistoPair2D)
MyTools.hh added functions accumulateForRndStudies(TH2D*,TH2D*) and accumulateForRndStudies_finalize(TH2D*,nExps)
Include/dir-Test/chkRndWithinErr.C : check HistoPair2D_t::randomizeWithinErr
Include/dir-Test/chkRndWithinErr2.C : check HistoPair2D_t::randomizeWithinErr and compare to MXSectD_t::AccumulateForAvg