Trellis plot: wrong encoding by shape (rplot.scaleshape)
The trellis plot shown in the documentation (http://pandas.pydata.org/pandas-docs/stable/_images/rplot7_tips.png) that uses ScaleShape to encode the data column "size" by shape shows a bug:

The same shape is used for "Sun, 5" and "Sun, 6" although they should have different shapes. Also "Thur, 4" and "Thur, 5" have the same shape (not visible in linked image).

The image also shows that gridlines are not correcly drawn on all panels.
