
Adds the possibility to change mark of a packet in userspace.
The ip_queue module is changed and a new function is added to 
libipq to decide and change the mark of a packet. 

This is used by the NuFW project (http://www.nufw.org).

***** WARNING ***** 
This patch breaks compatibility with the preceding version of libipq
and ip_queue module.
This patch also patch the userspace directory which means that you
you have to recompile and reinstall the iptables package after that.
