Energy window threshold for root #356

In "InputStreamFromROOTFIle.cxx":
this->parser.add_key("low energy window (keV)", &this->low_energy_window);
this->parser.add_key("upper energy window (keV)", &this->up_energy_window);

The the energy thresholds are given in keV. However, gate energies are stored in MeV. Either the energy or the energy window threshold need to be rescaled.
Currently this doesn't create any problem as the threshold values are set respectively to 0 and 1000.