Instead of having to manually document them, we can now let the RST dump
figure everything out.

Refs #3099

Instead, they are added where they are needed: only in error messages
involving them.

Refs #3099

Refs #3108

* clarify defaults
* document Transient

Fixes #3108

Fixes: #3086

Refs #2872

Otherwise it is considered a code block instead of a paragraph where it
is used.

The VSL query could in theory do that, but I don't think it was
actionable without double quotes to delimit empty fields or fields
containing spaces.

The test case covers the last field of Backend_health records.

When we output a VSL field containing spaces, all bets are off for VSL
queries relying on that field or subsequent fields in the same record.
The solution is to allow a quoted-string format for such fields.

- fix centos:7 distcheck
- use centos to build the dist tarball
- simplify git cloning with builtin command
- no need for ssh when building
- tar the dsc files with the deb ones
- use the regular pkg repo now that the alpine PR has been merged

brought up on IRC by @scn

It is only really needed for one last use case.

Inform users when the parameter we try to change depends on another
parameter.

This is not meant to be merged as-is, we could have a new VSB function
to trim the end of the string if it matches the one passed as the second
argument. In this case, we would trim the trailing newline only of the
CLI response didn't overflow in the first place, adding the extra
information on the same line. Alternatively we could also simply add the
explanation for the dynamic bounds on the next line.

Feedback welcome.

Fixes #3098

req->err_code and req->err_reason are set when going to synthetic
handling. From there the resp.reason HTTP field is set from
req->err_reason if set, or the generic code based on req->err_code is used
if it was NULL. This patch clears these members so that a value from the
handling of a previous request doesn't linger.

Fixes: VSV00004

This de-duplicates logic between the two hashing directors, and in
the case of vmod-shard adds a missing check for empty components in
the strands that should be skipped.

This breaks the hashing of the hash director, but unlike the shard
director it offers no stability and results may vary depending on the
health of individual clusters. For this reason only d00003.vtc needed
a bit of reshuffling.

I was in the neighborhood...

This reverts commit 6233b088.

Conflicts:
	bin/varnishd/cache/cache_req.c

The conflict was introduced with the handling of h2 stream 0 pseudo
request: 51127b46. This fixes a
regression where timeout_idle could be circumvented by a periodic
CRLF, except that it has no real consequence like holding onto a
worker thread thanks to timeout_linger kicking in as expected.

In addition to reverting the change, test coverage is added.

This reverts commit 762fda9a.