Restoration module

[Stéfan van der Walt]

Hi everyone,

Just a heads-up on a new scikit-image submodule: ``skimage.restoration``.

Thanks to François Orieux, we are fortunate to have the following
deconvolution algorithms implemented:

[1] `wiener`
[2] `unsupervised_wiener`
[3] `richardson_lucy`

I'd pay specific attention to Francois' own algorithm [2] -- no more
painful parameter tweaking to get a good Wiener-Hunt deconvolution!

Thanks also to everyone on the team who worked hard to review and shape this PR.

Stéfan