Adding an image.is_supported(suffix) function.
Adding an image.is_supported(suffix) function.

* so we can iterate through a directory of files, opening everything that's a
supported image type.  (e.g. when reading a dataset...)

* this also simplifies the big if statements in load and save... a minor upgrade maybe :-)

jonathantompson/image,colesbury/image,torch/image,Moodstocks/image,jagapiou/image