Instead of calling /sources.json and rendering the "Fetch source data"
box client-side in Javascript, call /sources.js so we can render the
html server-side.
Captioned post previews (previews with the pool name, similarity, or
size beneath) need to have `height: auto` set, otherwise they'll default
to `height: 154px` (just enough for the image) and the caption won't be visible.
* Consolidate blacklist css in one file.
* blacklist box: fix tag colors not dimming on hover.
* blacklist box: allow middle clicking on tags to open in new tab.
* /wiki_pages: move blacklist controls to top of tag sidebar.
* /wiki_pages: fix missing "disable all" / "re-enable all" buttons.
