We used to attempt to remove any port specification before recording
HTTP host headers in logs. Doing so would (1) remove potentially useful
information, (2) not match what the documentation seemed to suggest, and
(3) fail for IP6 addresses containing colons.
We now record the original HOST header as is.
Addresses #1844.
This makes conn.logs a bit prettier (and smaller) because all lines that
do not use a tunnel will now have a "-" instead of the "(empty)" for
tunnel_parents.
This changes the HTTP log format slightly but shouldn't mess
up anything that anyone was doing because the old "filename"
field was never actually filled out. Tests are updated as well.
