Updated get_bkg_stack.py to work since updates
Unimportant updates in tmp_check_edges.py
Attempt at modernizing train_basis_model.py

I ended up using train_superimposed.py instead, and putting the
sampling code there.
Many very experimental changes to train_superimposed.py.
View part probability now uses my own image viewer.

This makes it so that they're all saved in a single image.
Much easier to view and much faster to save.
Experimental changes in detector.py.
Minor updates.