Changes to the PM system

[Serval]

Since I noticed on another site that Spambots also use the PM system to send SPAM, I decided to take a few precautions to make the chance of abuse a bit smaller. This means that you can only send a PM once every 5 minutes.
Since we can not see if someone sends SPAM through the PM system, we do encourage to report such PM's to us, so we can take proper actions to ban spambots from the site.

[gamary]

Wilco, chief!