2013-06-24-wise/index.html: Cleanup HTML markup and indentation

* Add the testing section to the table of contents.
* Add missing <p>, <code>, and <pre> tags.
* Close unclosed tags (e.g. '<li>...' -> '<li>...</li>').
* Quote attribute values (e.g. '<font size=+1>' -> '<font size="+1">').
* Use &ndash; and &mdash; where appropriate.
* Consistently indent nested tag content with spaces.
* Remove trailing whitespace.

Due to the whitespace changes, the unified diff looks pretty
intrusive.  If you want to focus on the substantive changes, use:

  $ git diff --word-diff=color