  1. add transformation PDF + test/example   1. add `M2Q` and `Q2M` transfomoration variables/function
  1. add transformation PDF + test/example
  1. add `M2Q` and `Q2M` transfomoration variables/function

OstapHEP/ostap,OstapHEP/ostap,OstapHEP/ostap,OstapHEP/ostap