* Redesign details view.
The details view is now implemented with css grid, in a full-window
no-scroll layout (except for small screens, where the design is still
sequential and scroll is used)
This incudes some cleanup of the markup and corresponding changes in
the admin script.
* Update ructe to 0.12.0.
* Larger small and medium images.
* Slightly more pics per page in split lists.
* Use more OSM places.
* Update README.
* Improve async image scalig by using tokio spawn_blocking.
* Get size from actual image if it is missing in exif data.
* Add "close" link for the keyboard help.
* Improved db pool initialization.
* Some cleanup / refactoring.
* Add og metadata to image indexes.
* Update warp, use async/await.
* Lots of code cleanup and dependency clarification.
* Update ructe to 0.11.4.
* Update kamadak-exif to 0.5.x.
* Update image to 0.23.x.
* Update r2d2-memcached to 0.5.0.
* Disable legacy password hashers (all but pbkdf2 for now).
* Use more places from OSM.
* Calc function is fixed in rsass 0.11.2, remove workarounds.
* Refactor facet search.
* Some cleanup.
* Fix toggling for "pos" and "!pos" search.
* Implement negative searching: Seach for images with or _without_
specific tags, places or people.
* Rewrote GlobalContext.verify_key to get rid of some clippy warnings.
* Fix some warnings with rustc 1.37.
* Update structopt to 0.3, r2d2-memcache to 0.4.0, and ructe to 0.7.2.
* User "medallion" 2.3.1 instead of "jwt".
* Magic pos / !pos search.
* Make overpass API url configurable.
* Shorter db usage from pool.
Don't keep a db handle checked out from the pool for the entire
request, but instead check out one when needed. Hopefully, this means
it won't keep a db connection busy while scaling an image.
