Certain parts of comment rendering triggered sql queries that we didn't
really need to do. Rework things to avoid this.
* Preload comment creators in order to display commenter names with link_to_user.
* Preload comment votes in order to display "undo vote" links. Only preload
votes for members since anonymous users can't vote and don't have "undo
vote" links.
* Rework various conditionals to do the filtering in Ruby so that we
avoid issuing any extra queries in sql.
* Avoid issuing any queries at all when the post doesn't have any
comments (when last_commented_at is blank).
Also fixes a bug where mod actions weren't logged on mass updates.
Creating the mod action silently failed because it was called when
CurrentUser wasn' set.
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.
* Drop /posts?ro=true param (broken).
* Clean up tag_match (rescuing PG::ConnectionBad didn't do anything, we
just build the query here, we don't run it).
* Clean up javascript.
* Return HTTP 422 instead of HTTP 500 on "you have already voted for
this post" errors.
* In json/xml error responses, return the error message in the `message`
field, not `reason`.
* In json/xml success responses, return the post itself instead of a
plain `{ success: true }` object.
* Simplify code.
* Show backtraces for all users, not just builders.
* Show backtraces only for unexpected server errors (status 5xx), not
for normal client errors (status 4xx).
* Log expected errors at info level (reduce noise in production logs).
Fix it being possible to reject approved BURs, or to re-reject already
rejected BURs.
Rejecting an approved BUR wouldn't revert the aliases/implications, but
it would change the BUR's status to rejected.
* When creating an artist by clicking the '?' next to the artist tag in
the tag list, prefill the new artist form by finding the artist's last
upload and fetching its source data.
Previously we filled the urls with the source of the artist's last
upload, which was wrong because it was usually a direct image URL (#3078).
* Fix the other names field not escaping spaces within names to underscores.
* Fix the other names field being potentially prefilled with duplicate names.
