Created on 18 sep. 2012
TODO it would be nice if for lines you can select either markers, gray scale, or simple black
Take each axes in the figure and transform its content to black and white. Lines are tranformed based on different line styles. Fills such as can be used in meth:envelopes are gray-scaled. Heathmaps are also gray-scaled.
derived from and expanded for my use from: http://stackoverflow.com/questions/7358118/matplotlib-black-white-colormap-with-dashes-dots-etc