A quick fix to this issue will be to comment out the following code in modules/IRC.php


763
                        // Strip any control characters that might be lingering before we send out.
 
764
                        $txt = preg_replace('/[^(\x20-\x7F)]*/','', $txt);

You might get some control character showing up ingame if you have multiple bots sitting in the IRC channel, but it will allow Æ Ø and Å again.