on sockets, so that we can correctly handle multiple sockets between
two hosts.

The version of output used is controlled by the new
LIBNETMON_OUTPUTVERSION environment variable. The old output is
version 1, which is the default for now. The new version is 2.

Version 2 is still in ASCII. The address format has chaged from
'remoteip.remoteport' to 'localport:remoteip:remoteport'.

Version 2 will soon get the ability include information about when
sockets are created and destroyed.