Bumping this feature request.
Over at Stonehearth we frequently have users post screenshots from their games, and at the moment, this is done through a variety of means. Some post links to Imgur albums, or other specialized sites, but most simply upload their images directly. Most images are HD or better, which results in them being lightboxed (good), but you have to open each one individually and scroll each time (bad). A better system in core for viewing multiple images would be great.