Add missing tests in math core. Fix stressGoFtest compilation
Add FindBin(x) function in TKDTreeBinning. Add also a test for TKDTreeBinning
Fix the AD GoF test for a bug in integer overflows. Use also now tables from R code from kSamples package to compute the p value. This fixes ROOT-6666
Update reference values, by computing expected values using R.
skip test if math more is not present