BUGFIX: [img] tag chat crash quick patch

This is a dirty patch to prevent users from crashing every chatters browser by sending ...

[img]http://example.com/some-image-link.jpg
[/img]

... take notice of the carriage return. If this is sent it disables the chat until the message is edited or removed from the database. This is probably not the best way to accomplish but it is functional. I am hoping this will no longer be an issue once the new parser is implemented but thought O should send this just in case its been overlooked o.O

This patch (or a cleaner version) should be applied to all AJAX-Chat versions and branches 0.8.7 and below.