Replaces --dpi option in PCoA.py with --figsize.
Replaces --dpi option in PCoA.py with --figsize.

Instead of setting the DPI of a figure, which is often difficult to
mentally map to the actual image size, PCoA.py now allows
users to explicitly set the matplotlib figsize parameter (inches).

smdabdoub/phylotoast,akshayparopkari/phylotoast