   1. add test `test_fitting_toys_simfit.py`    1. further extend `Ostap::Math::DaltzIntegrator`
   1. add test `test_fitting_toys_simfit.py`
   1. further extend `Ostap::Math::DaltzIntegrator`

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