logparse.pl: option to pass through Event Log entries.

This makes it more feasible to use logparse.pl as an output filter on
a PuTTY SSH log file and discard the original file.

In particular, ever since commit b4fde270, I've been finding it
useful when testing new code to direct my SSH logs to a named pipe and
have another terminal window give a real-time dump of them by running
'while cat $named_pipe; do :; done'. Now I can replace the 'cat' in
that shell command with 'logparse.pl -ve' and still get the Event Log
messages as well as the unpacked contents of all the packets.