New headers and parameters from RFC 3455 and UUI drafts

These changes derive from mail by John Gregg (see http://list.resiprocate.org/archive/resiprocate-devel/msg08665.html). I added additional header to exchange User-to-User information via SIP.
I tried with the old -k on my windows 3.0.1 grep binary and it didn't work.  Which leads me to questions how I used this batch file before.  The new --key-positions worked good for me too.  I think we should keep this change.