This patch contains the change API and other modifications required for 
the nfnetlink_conntrack. It applies on top of the ct-event-API.

I guess that this is heavy going to review but I don't see another way 
to such a patch.

Since this won't ever become part of ip_conntrack. Would it be worth it 
posting small patches with modifications for nf_conntrack to make fit 
requirements of nfnetlink_conntrack in future?