o Log the (payload/size) of all packet types, not just TCP packets

o  Log the (payload/size) of all packet types, not just TCP packets

o  If the new ``filter-decapsulation'' is enabled, delve into UDP packets
   that contain 0xff 0x03 as the first two bytes, and if we recognise it
   as PROTO_IP, decapsulate it for the purpose of filter checking.

   If we recognise it as PROTO_<anything else> mention this for logging
   purposes only.

This change is aimed at people running PPPoUDP where the UDP traffic is
being sent over another PPP link.  It's desireable to have the top level
link connected all the time, but to have the bottom level link capable
of decapsulating the traffic and comparing the payload against the filters,
thus allowing ``set filter dial ...'' to work in tunnelled environments.

The caveat here is that the top ppp cannot employ any compression layers
without making the data unreadable for the bottom ppp.  ``disable deflate
pred1 vj'' and ``deny deflate pred1 vj'' is suggested.