Piper Plot

[flashliquid]

I frequently use a special combination ternary diagram called a "Piper Plot" link. This is used frequently in Earth/Environmental sciences but I have not found a means to generate one in Python. Do you think it is something you might pursue?
Cheers

[marcharper]

Happy to merge a PR with this functionality but it's unlikely that I'll have time to do this in the near future. My personal use of the library is mostly for biological applications, and it's more likely that I would add contour plots (the most requested feature).