Coordinates for region drawing

[freeman-lab]

The coordinates underlying the image plot type might be flipped in y compared to the expected coordinates system. For example, if drawing a region during the following:

lgn = Lightning()
viz = lgn.image(random.randn(200,100))
bounds = asarray(viz.coords[0])

If we then plot the coordinates as a scatter plot, the result is flipped in y relative to how the region looks in the image:

lgn.scatter(bounds[:,0], bounds[:,1])

This could probably be fixed just by manipulating the transform by which points in image coordinate space are extracted from the polygon regions.