Merge from v5-34 patches: commits: 8d926912c989529ff2b979bda68959279ae1614e and 78b84e3b315ab12350409b2d9e2afc7fb980f0e4

Multiple modifications in stressFit.cxx:
- switch from TVirtualFitter to ROOT::Math::Minimizer
- successful trial means found minima is within predefined epsilon (before was arguments are close to the minimum's position). This modifies ROOTMARKS value
- StatusPrint reports number of successes out of the trials number