Merge pull request #422 from ReactionMechanismGenerator/fixmplbackend

remove deprecated warn keyword

arc/plotter.py

@@ -6,7 +6,7 @@
 # Force matplotlib to not use any Xwindows backend.
 # This must be called before pylab, matplotlib.pyplot, or matplotlib.backends is imported.
 # Do not warn if the backend has already been set, e.g., when running from an IPython notebook.
-matplotlib.use('Agg', warn=False, force=False)
+matplotlib.use('Agg', force=False)
 import matplotlib.pyplot as plt
 import numpy as np
 import os