Remove the `preview_urls` method from strategies. The only place this was used was
when doing IQDB searches, to download the thumbnail image from the source instead of
the full image.
This wasn't worth it for a few reasons:
* Thumbnails on other sites are sometimes not the size we want, which could affect
IQDB results.
* Grabbing thumbnails is complex for some sites. You can't always just rewrite the
image URL. Sometimes it requires extra API calls, which can be slower than just
grabbing the full image.
* For videos and animations, thumbnails from other sites don't always match our
thumbnails. We do smart thumbnail generation to try to avoid blank thumbnails, which
means we don't always pick the first frame, which could affect IQDB results.
API changes:
* /iqdb_queries?search[file_url] now downloads the URL as is without any modification.
Before it tried to change thumbnail and sample size image URLs to the full version.
* /iqdb_queries?search[url] now returns an error if the URL is for a HTML page that
contains multiple images. Before it would grab only the first image and silently
ignore the rest.
* Fix a bug where creating posts failed if IQDB wasn't configured.
* Fix broken Skeb test caused by changed URL.
* Fix broken IP geolocation tests caused by API returning different data.
* Fix broken post regeneration tests.
Fix the upload page so that it shows similar images (IQDB matches) for
files uploaded from your computer. Before this only worked for files
uploaded from a source.
Show the length of videos and animated posts in the thumbnail. The
length is shown the top left corner in MM:SS format. This replaces the
play button icon.
Show a speaker icon instead of a music note icon for posts with sound.
Doing this requires doing `.includes(:media_asset)` in a bunch of
places to avoid N+1 queries when we access the post's duration.
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.
