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.
Refactor the post preview html to use the ViewComponent framework. This
lets us encapsulate all the HTML, CSS, and helper methods for a UI
component in a single place.
See https://viewcomponent.org.
Fineprint text was variously styled with `.info`, `.tn`, `.hint`, or
`.cost-footnote` css classes. Standardize on `.fineprint` instead. Use
`.hint` only for form hints and `.tn` only for <tn> tags in translation
notes.
Incidentally changes the font size of form hints to 0.8em (was 0.7em)
and the color of fineprint to #888 (was #AAA or #666).
* On the /uploads/new page, instead of just showing a "This post has
probably already been uploaded" message, show the actual thumbnails of
posts having the same source as what the user is trying to upload.
* Move the iqdb results section up top, beside the related posts section.
