Fill out the matplotlib and seaborn columns

Matplotlib covered 2 of the 13 plots and classic seaborn 5. Add cells so
matplotlib covers 12 and seaborn all 13, matching each reference plot's
titles and labels. Where matplotlib has no primitive (faceting, stacking,
dodging, KDE, loess) the cell does the work by hand and says so in a note.

Matplotlib skips scatter-with-regression: an OLS fit with a 95% confidence
band is a dozen lines of statsmodels and two of matplotlib, so it would
demonstrate statsmodels rather than matplotlib.

Author: tdhopper