new file:   MoreNodeGenerators.py
interim commit with skeleton generator, sans actual algorithm.
interim commit, basic algorithm but sans end cases!
interim commit. complete but untested equal spaced shells generator
interim commit. possibly a decent generator for equi-distant spherical shells.
comments only
leaving figure windows open in interactive sessions
pressure histogram quick plot and changing plotted pressure values to GPa
always using a fresh figure window. probably want to make that selectable
saving a record of original script with the output dumps
docstring edits
more docstring edits