Replace generic comments system with a more advanced options functionality.

= Features: =

- Change order (Oldest First / Newest First)
- Add comments block always directly after content
- Control limit
- Use autoloading of comments (when more scrolls into view, next x comments are automatically loaded)
- jQuery loading of more comments (no more page reloads)
- Order, Limit and Auto-Load preferences are saved per object type (file, blog, page etc)
- Preferences for logged out user are stored in session (not in cookies)