Windowed histogram

Implemented skimage.filter.rank.windowed_histogram, along with required changes to fitler.rank machinery.
@ahojnnes -- what are we doing about multiple files in the API changes folder?

On Tue, Sep 2, 2014 at 1:22 AM, Stéfan van der Walt <stefan@sun.ac.za> wrote:
>
> I think "an N-dimensional" is acceptable--since we say it "an
> en-dimensional".