Bootstrapping enhancements

[kreisl]

• Add QA plots
  • distribution of bootstrapping sample means
  • convergence of bootstrapped uncertainties
• Select number of samples used to evaluate bootstrapped uncertainties

[eugene274]

Hi!
As a first step I'd give user (at least read) access to bootstrap samples.
We've already discussed with Ilya and Mikhail (HADES) and Oleksii (CBM), that access to bootstrap samples can be useful for several analyses.
For example:

• fitting of dv1/dy
• v1 signal for signal and background (flow of weak decays)