Add option to specify list of edge colors when drawing with matplotlib.
Add option to specify list of edge colors when drawing with matplotlib.

Use:

G=path_graph(5)

draw(G,edge_color=['k','b','r','y'])

Fixes #144.

--HG--
extra : convert_revision : svn%3A3ed01bd8-26fb-0310-9e4c-ca1a4053419f/networkx/trunk%40720

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