[Nitro] forum bugs

[Antoniolo]

- when you supply nothing or a wrong number to (anti-spam-system), it
doesn't generate a new one;
- 'post new topic' button should show a little hand when mouseover;
- when you reply a post and supply a wrong number or whatever, the new form
erases all my text.
- why using lots of reply buttons when we only need just one? I originally
thought they would bring a quoted text... but they don't do that at all.