NOCC brakes message threads on reply

Hi ;-)

At the moment NOCC brakes message threads on reply. This is because 'replies' are just handled like a 'new' message, with the difference that some form fields are pre-filled.

This patch enables NOCC to pass the old message_id to the send form and adding the additional fields 'References:' and 'In-Reply-To:' to the message header on reply.

And this time, I will add a valid patch. ;-)

Sincerly regards,

Tobias Mathes.