version, the unique identifier is the pid + fd, rather than anything
involving port numbers. UDP sockets won't necessarily have any of
that.

I've made a few tweaks to Jon's v3 format. The format is not
finalized, so some details could still change.

Added preliminary support for UDP sockets. Right now, only handles
sockets that are connect()ed, not ones that are used with sendto().
We need to decide what the best way to report on sendto() is.  UDP
support can be enabled by passing the new '-u' argument to netmond.

Needs support for handling applications that fork(), since the PID
changes. Shouldn't be too hard, just one more syscall to wrap.

At some point, we should stop supporting earlier output versions,
because that will allow me to clean up a lot of code.