in particular to find varnishncsa

do that any more. But will have to revisit the formatting, because
Varnish VSL and its tools apparently don't use VSB_quote for binary
data any more.

tag to be read for a specific header, but also the first occurrence of
the tag. For example when both %{Varnish:first_byte}x (which requires
Timestamp:Resp) and %{tag:Timestamp}x (without a header specifier)
appear in the output format.

only calls VSB_quote() for the payload if the payload contains a
non-printable character (for somewhat better compatibility with
varnishncsa).

with varnishncsa

The test for varnishncsa compatibility is restored, since varnishncsa
in 4.1.0 has the -r CLI option back.
Using a new binary log file for tests, now much shorter.

add --enable-debugging to set -O and -fno-inline for debugging