Static figures

Any figures that rely on optional system configurations need to be handled a

little differently. These figures are not to be generated during the

documentation build, in order to keep the prerequisites to the documentation

effort as low as possible. Please run the :file:`doc/pyplots/make.py` script

when adding such figures, and commit the script **and** the images to

git. Please also add a line to the README in doc/pyplots for any additional

requirements necessary to generate a new figure. Once these steps have been

taken, these figures can be included in the usual way::