Matplotlib future error

[nikohansen]

This will fail to work with future versions of matplotlib, hence should be fixed, also because it floods the screen with tons of annoying warnings.

/anaconda3/lib/python3.7/site-packages/cocopp-2.3.3.18.11-py3.7.egg/cocopp/ppfig.py:574: MatplotlibDeprecationWarning: Saw kwargs ['ls', 'linestyle'] which are all aliases for 'linestyle'.  Kept value from 'linestyle'.  Passing multiple aliases for the same property will raise a TypeError in 3.3.
  res2 = plt.plot(x2, y2, **marker_args)

It's kind-of tricky to understand where this comes from though.

[nikohansen]

Fixed in the development branch.

[georgedeath]

Here is the commit that fixes it, in case people were struggling to find the code.