Change calling convention to explicitly indicate whether the attributes
are for the <th> element or the <td> element. Fixes various cases where
the two were mixed up.
* Fix .col-expand classes not being set correctly on the /post_versions,
/pool_versions, and /notes pages.
* Fix .updater and .updated-at classes not being set correctly on the
/forum_topics page.
* Fix the name param being ignored (noticeable in the post count field
on the /tags page).
* Don't pass empty string when column has no name.
* Factor out common sidebar layout template.
* Convert wiki pages and posts to use this template.
* Add data-layout attribute to <body> element indicating the current layout.
Changes to the /wiki_page_versions global listing:
* Add "diff" links that show you what changed in the given edit.
* Add "?" links that take you to the current version of the wiki.
* Add "»" links next to wiki page titles that take you to the wiki's full edit history.
* Add "»" links next to usernames that take you to the user's full edit history.
* Add a "Status" column that shows whether the wiki page was created,
deleted, undeleted, or renamed.
* Link to /wiki_page_versions in sidebar, not /wiki_pages?order=time.
Split the wiki page versions template into two partials,
_global_listing.html.erb and _page_listing.html.erb, to avoid the nested
conditionals that arise from combining these two pages into one template.
Add html IDs to distinguish between these two partials.
It seems that in Danbooru 1 wiki page version's created_at was always
the initial created_at of the wiki page itself, as opposed to the time
that the edit was made like in Danbooru 2.
