* On /pools, hide deleted pools by default in HTML responses. Don't
filter out deleted pools in API responses.
* API change: on /forum_topics, only hide deleted forum topics by
default for HTML responses, not for API responses. Explicitly do
https://danbooru.donmai.us/forum_topics.json?search[is_deleted]=false
to filter out deleted topics.
* API change: on /tags, only hide empty tags by default for HTML
responses, not for API responses. Explicitly do
https://danbooru.donmai.us/tags.json?search[is_empty]=false to filter
out empty tags.
* API change: on /pools, default to 20 posts per page for API responses,
not 40.
* API change: add `search[is_empty]` param to /tags.json endpoint.
`search[hide_empty]=true` is deprecated in favor of `search[is_empty]=false`.
* On /pools, add option to show/hide deleted pools in search form.
* Fix the /forum_topics page putting `search[order]=sticky&limit=40` in
the URL when browsing past page 1.
2eb89a8354