For small thumbnails, use 180x180 thumbnails scaled down to 150x150.
This is so we can get rid of 150x150 images and just use 180x180 for
both small and medium size thumbnails.
Also fix RSS feeds, XML sitemaps, and Discord embeds to use 360x360
thumbnails instead of 150x150 thumbnails.
Changes:
* Drop Users.id_to_name.
* Don't cache Users.name_to_id.
* Replace calls to name_to_id with find_by_name when possible.
* Don't autodefine creator_name in belongs_to_creator.
* Don't autodefine updater_name in belongs_to_updater.
* Instead manually define creator_name / updater_name only on models that need
to return these fields in the api.
id_to_name was cached to reduce the impact of N+1 query patterns in
certain places, especially in api responses that return creator_name /
updater_name fields. But it still meant we were doing N calls to
memcache. Using `includes` to prefetch users avoids this N+1 pattern.
name_to_id had no need be cached, it was never used in any performance-
sensitive contexts.
Avoiding caching also avoids the need to keep these caches consistent.
Use the "\A" metacharacter for the beginning of a string, instead of "^"
for the beginning of any line within that string, and check for "://" as
well. Fixes#1947.
added paragraph tag containing post.tag_string as child element of div inside content; also, as minor edit, modified post/atom to posts.atom and post/index to posts in the link href.
