Make upvotes public the same way favorites are public:
* Rename the "Private favorites" account setting to "Private favorites and upvotes".
* Make upvotes public, unless the user has private upvotes enabled. Note
that private upvotes are still visible to admins. Downvotes are still
hidden to everyone except for admins.
* Make https://danbooru.donmai.us/post_votes visible to all users. This
page shows all public upvotes. Private upvotes and downvotes are only
visible on the page to admins and to the voter themselves.
* Make votes searchable with the `upvote:username` and `downvote:username`
metatags. These already existed before, but they were only usable by
admins and by people searching for their own votes.
Upvotes are public to discourage users from upvoting with multiple
accounts. Upvote abuse is obvious to everyone when upvotes are public.
The other reason is to make upvotes consistent with favorites, which are
already public.
1a27b1d5eb