Strenghen the case against STRING_LIST in the docs.

See also: #2873

Conflicts:
	lib/libvmod_debug/vmod.vcc

Conflicts:
	lib/libvmod_blob/hex.c

Re-implementations of the current functions for STRING_LIST.

Closes #2733

Conflicts:
	include/vrt.h
	lib/libvmod_debug/vmod.vcc
	lib/libvmod_debug/vmod_debug.c

This introduces VRT 7.1 for the 6.0 releases.

Fixes #2846

Fixes #2880

Fixes #2879

This has bugged me (slightly) for ages.

Too trivial to warrant its own line(s) in test-case/u00008.vtc.

Should address "HTTP cache must not reuse a response with an invalid
Cache-Control: max-age (trailing alpha)" from https://cache-tests.fyi.

Should address "HTTP cache must not use a cached response with
Cache-Control: No-CaChE, even with max-age and Expires" from
https://cache-tests.fyi.

Fixes: #2874

Fixes #2871.

Conflicts:
	bin/varnishd/cache/cache_fetch.c

Submitted by:   Frederic Lecaille <flecaille@haproxy.com>

It turns out people are really attached to their varnish.params file.

See `git grep PROXY -- bin/varnishd/mgt/mgt_main.c`.

A regression from d7a81fe8 and the
followup changes from #2993. The new VSS_Resolve{One,First} functions
expect a non-null address string.

Conflicts:
	lib/libvmod_std/vmod_std_conversions.c

Conflicts:
	lib/libvmod_std/vmod.vcc

Conflicts:
	bin/varnishtest/tests/m00011.vtc
	lib/libvmod_debug/vmod.vcc
	lib/libvmod_debug/vmod_debug.c

And sync the documentation with the current behavior, part of which used
to be implicit.

Conflicts:
	lib/libvmod_std/vmod.vcc
	lib/libvmod_std/vmod_std_conversions.c

Conflicts:
	lib/libvmod_std/vmod_std_conversions.c

This is how std.ip is documented, so VSS_ResolveOne doesn't work there.
It might not be the only migration to VSS_ResolveOne that requires
attention.

Speaking of attention, VSA_Malloc may require some.

Conflicts:
	lib/libvmod_std/vmod_std_conversions.c

It can now be shared by established callback-based resolvers and the new
VSS_ResolveOne. This also changes the semantics of VSS_ResolveOne in the
sense that the port is now a default port, overriden by the address if
it contains one.

Also make it clear that VTCP was already relying on a VSS function that
didn't and still doesn't allow a null errp argument, while conversely
all VTCP_open call sites provide a valid errp argument.

At this point the workspace already overflowed so there's no point
making further progress to fail on the next workspace operation.

Incidentally, we are failing for an IP conversion, not an integer.

Conflicts:
	lib/libvmod_std/vmod_std_conversions.c