CAPTCHA for opening new threads

Issue description

Seems like a bot posted around 250 threads with inappropriate content. Adding a captcha to create new topics could help to prevent this.

Issue comments

Thank you for your report. We have removed the content of this user.

The issue is that most of this content is not even posted by bots and we can't catch these types with CAPTCHA.

Although this user definitely is a bot. And CAPTCHA is punishment for all users so this is our resort only if we are under spam attack.

We have filters to catch spam posts and we will try to improve these.

New reporting and flagging system for such posts is in work too :)

Most of the time they link to their websites. This way their websites get a better reputation with search engines because their websites are linked to by a reputable website (MCreator's in this case).