Replace the old IQDB API client with a new client for the new forked
version of IQDB at https://github.com/danbooru/iqdb.
Changes:
* The /iqdb_queries endpoint now returns `hash` and `signature` fields.
The `signature` is the full decoded Haar signature, while the `hash`
is a encoded version of the signature.
* The /iqdb_queries endpoint no longer returns `width` and `height`
fields in the response (these were always 128x128).
* We no longer need the IQDBs frontend server, now we talk to the IQDB
instance directly.
* We no longer send add/remove image commands to IQDB through AWS SQS,
now we send them to IQDB directly. They are sent in a delayed job so
that if IQDB is down, uploading images is still possible, the add
image commands will just get queued up.
* Fix a bug where regenerating an image's thumbnails didn't regenerate
IQDB, because IQDB silently ignored add image commands when the image
already existed in the database.
Regenerate posts asynchronously using a delayed job.
Regenerating a post can be slow because it involves downloading the
original file, regenerating the thumbnails, and redistributing the new
thumbnails back to the image servers. It's better to run this in the
background, especially if a user is trying to regenerate posts in bulk.
The downside is there's no notification to the user when the regeneration
is complete. You have to check the modactions log to see when it's finished.
* Remove the PostRegeneration model. Instead just use a mod action
to log when a post is regenerated.
* Change it so that IQDB is also updated when the image samples are
regenerated. This is necessary because when the images samples are
regenerated, the thumbnail may change, which means IQDB needs to be
updated too. This can happen when regenerating old images with
transparent backgrounds where the transparency was flattened to black
instead of white in the thumbnail.
* Only display one "Regenerate image" option in the post sidebar, to
regenerate both the images and IQDB. Regenerating IQDB only can be
done through the API. Having two options in the sidebar is too much
clutter, and it's too confusing for Mods who don't know the difference
between an IQDB-only regeneration and a full image regeneration.
* Add a confirm prompt to the "Regenerate image" link.
