JKH: tcpdump improvement

Hello Poul,

I want to try to implement portrange feature in tcpdump as described on your 
JKH TODO list if it's still actual.

I have several thoughts about this task.

1. As soon as it is neccessary to implement port<N, port>N to implement this 
task it is a good idea to extend syntax with these operators. Actually after 
implementing "<" and ">" operators task is 80% done because it is possible to 
implement range by "port > N1 and port < N2" expression.

2. About range operator. I'd prefer to add functionality to existing "port" 
operator instead of introducing new keyword "portrange".
It seems easier to remember and use syntax like:
"port 40-400 and port 500"

What do you think?

Thanks
Vadim Chekan.