Run PyROOT in batch mode

When running in batch mode, PyROOT does not display any graphics. You can activate the batch mode as follows:

1. Pass -b as a command line argument, for example, python -b <yourscript.py>. For this work you must set ROOT.PyConfig.IgnoreCommandLineOptions = False inside the PyROOT script.

2. Call gROOT.SetBatch in the PyROOT script right after importing ROOT

    import ROOT
    ROOT.gROOT.SetBatch(True)