prune the number of image interpolations and replace with new material

[jimustafa]

Based on #80 (comment), there may be an opportunity to reduce the number of image interpolation methods that are demonstrated, and make room for new material.

[rougier]

I agree that a 3x3 (9 filters) would be enough and we'll have some space for other stuff. Which filters do we select ? I would go for: None, nearest, bilinear, bicubic, spline16, catrom, mitchell, gaussian, lanczos

[jklymak]

Well, matplotlib uses 'hanning' by default when downsampling now, so maybe should include that ;-)