singleton third dimension with mmap=true

[bjarthur]

julia> img = TiffImages.load("myimage.tif");

julia> size(img)
(10512, 6336)

julia> img = TiffImages.load("myimage.tif", mmap=true);

julia> size(img)
(10512, 6336, 1)

julia> img = ImageMagick.load("myimage.tif");

julia> size(img)
(10512, 6336)

[tlnagy]

Good catch, mmap should be consistent with normal loading on this.

[tlnagy]

It appears that I built the mmap type with the assumption that folks will only use it for 3D images because it doesn't make too much sense otherwise, since the primary benefit is loading the image 2D slice by 2D slice.

I guess I could parameterize the type on the number of dimensions and then have a trivial mmap type for the 2D case.