Fix bug related to theme URLs in the dashboard
If a URL is provided in a theme's `about.php` file, it would be output in the dashboard using the `url()` function, with the first argument being the theme name and the second being the URL. That however won't work—there seems to have been a mix up between `url()` and `anchor()`.
Merge pull request #1804 from vanillaforums/hotfix/theme-settings-url

Fix bug related to theme URLs in the dashboard