Topic: [Feature] API - if post is in pool, get pool ID

Requested feature overview description.

Using the api to show all details of a post https://e621.net/post/show.json does not show 1) if the post is in a pool 2) what id that pool would then have.

As of 2019-08-07, the information you can get for a post is: id, tags, locked_tags, description, created_at, creator_id, author, change, source, score, fav_count, md5, file_size, file_url, file_ext, preview_url, preview_width, preview_height, sample_url, sample_width, sample_height, rating, status, width, height, has_comments, has_notes, has_children, children, parent_id, artist, sources

Why would it be useful?

Sorting downloaded posts automatically in corresponding folders when using the API.

What part(s) of the site page(s) are affected?

post/show and post/index API

Updated by NotTheZorro