Appearing on search and album pages, the tray is where you can
remove items from your clipboard without having to click on its
checkbox -- that photo card may not even be on the current page.
More careful uncaching of the summed bytes, to minimize
recalculation. Fewer cases where the album itself
is removed from the photodb's getter cache.
This also helps the download link on album pages disappear if
the child albums don't actually have any photos.
New frontends folder will hold all front-end interfaces for etiquette. Existing flask site moved here and refers to itself as a package with external launcher. etiquette_site renamed to etiquette_flask