Merge remote-tracking branch 'origin/dev-input-transform-plotting' into dev-input-transform-plotting

* invert_activation for significance scans
* better plotting range for integer variables in plot_input

* 'master' of gitlab.physik.uni-muenchen.de:Nikolai.Hartmann/KerasROOTClassification:
  turn back on division by mean weight
  make total weight more consistent
  option to evaluate before activation
  python3 compatibility
  model plotting and alternative significance plot
  Improve loading from dir