Does anyone use quickhash-1?

[Benjamin Gilbert]

Hi all,

OpenSlide provides an `openslide.quickhash-1` property that's meant to
uniquely identify a slide file without performing a cryptographic hash
over all the data.  It isn't always provided (notably for TIFFs with
large top levels) but usually is.

Does anyone use this?

quickhash-1 must be carefully defined for each new slide format and
then kept stable, even as we learn more about the format.  For
example, we have two quickhash-1 definitions for Leica, depending how
many main images are in the slide.  As a result, the quickhash is a
recurring source of development headaches, and meanwhile I'd guess
it's never been used outside of its original application at CMU.

If you use the quickhash, or would like to use it but currently don't,
please speak up.  If there's very little interest I might consider
deprecating it for eventual removal.

Best,
--Benjamin Gilbert