Show the close description on the diff viewer page.

The close description was only shown on the review request page,
not on the diff viewer page, despite showing the banner. This now
adds the close description there as well.

Fixes bug #2913
Merge branch 'release-1.7.x'
Fix some more style issues with rendered Markdown text.

This fixes the lists to wrap correctly. We're back to native bullet
points, but now things line up correctly. Nested lists also now work,
whereas before they were flat.

The pre-wrap white-space mode has been turned off for all non-code
elements, fixing some other spacing problems.
Show a spinner before rendering markdown text or diff index.

When displaying a review request, there's a brief moment of time before
Markdown gets rendered or before the diff table is loaded where things
look wrong. For the Markdown fields (namely the Description and Testing
Done fields), the raw Markdown is shown first, and then switches to the
rendered text, which looks bad. The diff index shows a big line before
displaying its contents.

These now are marked as loading at first, and we'll show spinners. Once
the page has successfully loaded, the spinners go away and the rendered
content appears.

We also try to render the text for these fields a bit sooner than we did
before, hopefully reducing the load time.
Fix the grip image on the comment dialog.

When we added the jquery-ui stylesheet, and upgraded jquery-ui, it broke
our custom grip image on the comment dialog. That image remained, but an
arrow overlayed it.

This brings it back, and in a cleaner way. We don't add it through
JavaScript anymore. Instead, we just set the CSS rule for that icon.

It now looks as it did in earlier versions.
Set the rich-text info for new replies.

Replies were properly stored as rich-text, but the elements being
created for them didn't represent that, requiring a reload to see the
rendered markdown content. We now set this on the template for replies.
Fix a breakage with the recent close description fix.

The recent close description fix didn't default a variable, breaking the
diff viewer due to a "referenced before assignment" error. This is now
fixed.