Update documentation of TH1::GetEffectiveEntries
Fix problematic error handling and always rollback transaction. Fix ROOT-5262.

Fix problematic error handling and always rollback transaction instead
of trying to commit.
  o RooAbsPdf

    - In plotOn(), flag Normalization commands added to command line passed to RooAbsReal::plotOn() explicitly as such

  o RooAbsReal

    - In plotOnWithErrorBand() explicitly strip internal normalization commands from the plot argument list to be
      able to propagate uncertainties on the expected event count normalization, if requested
Merge branch 'v5-34-00-patches' of https://root.cern.ch/git/root into v5-34-00-patches
Use the tree pointer passed as argument of the TTreeViewer constructor, instead of using gROOT->FindObject(treeName), that can return the tree in memory (same name, but different cycle) instead of the selected one (fixes Jira #ROOT-5113)
Fix compilation warning: format %lx expects argument of type long unsigned int, but argument 2 has type TTree*