HypoTestCalculatorGeneric:

  add possibility to re-generate the same toys for getting the test statistics distribution for the alternate

ToyMCSampler: 

  set the parameters for evaluating the test statistics after generating the toys not before. 
  It should be the same within ROoStats because ToyMCSampler::fParametersForTestStat are the null POI, which are anyway re-set in 
  ToyMCSampler::Generate.   However it was a problem for combine ("CMS")


git-svn-id: http://root.cern.ch/svn/root/trunk@48176 27541ba8-7e3a-0410-8455-c3a389f83636