* Add a `rename A -> B` command for bulk update requests.
* Change mass updates to only retag the posts, not to move saved
searches or blacklists.
A tag rename does the same thing an alias does, except it doesn't
create a permanent alias. More precisely, a tag rename:
* Moves the wiki.
* Moves the artist entry.
* Moves saved searches.
* Moves blacklists.
* Merges the wikis, if both tags have wiki pages.
* Merges the artist entries, if both tags have artist pages.
* Fixes links in wiki pages to point to the new tag.
* Retags the posts.
Format scripts on the BUR index page as dtext, the same way they're
formatted in forum posts. This means that tags have colors and underlines,
but they don't have post counts. Gathering post counts was too slow.
* Remove the single alias and implication request forms. From now
on, bulk update requests are the only way to request aliases or
implications.
* Remove the forum topic ID field from the bulk update request form.
Instead, to attach a BUR to an existing topic you go to the topic then
you click "Request alias/implication" at the top of the page.
* Update the bulk update request form to give better examples for the
script format and to explain the difference between aliases and
implications.
