suzerain: add more stats, fix stats for species diffusivities

git-svn-id: https://svn.ices.utexas.edu/repos/pecos/suzerain/trunk@42761 0bd85f0b-c151-43b9-a1e9-27231104551f
suzerain: move notebooks/ to toplevel

git-svn-id: https://svn.ices.utexas.edu/repos/pecos/suzerain/trunk@42793 0bd85f0b-c151-43b9-a1e9-27231104551f