exposed to_string for buffer_region
fixed bug #1523585: skip nans in semilog plots
Add NumPy 1.0 compatibility
Quadmesh bugfix in backend_bases; prevent vmin==vmax in set_[xy]lim.
Collections support 2-D numerix arrays for path segments.
added selective autoscale for x and y axis
prevent name collision between numpy and other headers
Partial support for polygons with fill-only or boundary-only.
applied Andrew Straw's numpy patch
added nolegend patch for errorbars
