WIP: Describe array order terminology in 2D, 2D+c, 3D, 3D+c arrays

Still working on it, but just thought I'd check this in so that we can tag it as 0.11.
@tacaswell the array gets transposed back to front, so the comparison is already apples-to-apples. I like to have a "special" dimension because I think that is a common use-case: process each frame in an anisotropic volume separately in a loop. Having all dimensions be the same length might lead one to wonder why we are iterating in the first place.