gnu: services: use seconds instead of duration strings.

* gnu/services/dns.scm (zone-file, knot-policy-configuration): Use numbers
instead of duration strings.
(verify-knot-policy-configuration): Fix typo.
* doc/guix.texi (DNS Services): Update documentation.

services: network-manager: Specify a default value.

* gnu/services/networking.scm (network-manager-service-type)[default-value]:
New field.

services: cuirass: Extend rottlog with log rotations.

* gnu/services/cuirass.scm (cuirass-log-rotations): New procedure.
(cuirass-service-type): Use it to extend ROTTLOG-SERVICE-TYPE.

services: rottlog: Make extensible.

* gnu/services/admin.scm (rottlog-service-type)[compose, extend]: New
fields.
* doc/guix.texi (Log Rotation): Mention extension.

services: rottlog: Define <log-rotation> objects.

* gnu/services/admin.scm (<log-rotation>): New record type.
(syslog-rotation-config, simple-rotation-config): Remove.
(%default-rotations): Define as a list of <log-rotation> objects.
(log-rotation->config, log-rotations->/etc-entries): New procedures.
(<rottlog-configuration>)[periodic-rotations]: Remove.
[rotations]: New field.
(rottlog-etc): Use 'log-rotations->/etc-entries'.
* doc/guix.texi (Log Rotation): Update accordingly.

services: guix: Add 'max-silent-time' and 'timeout'.

* gnu/services/base.scm (<guix-configuration>)[max-silent-time]
[timeout]: New fields.
(guix-shepherd-service): Honor them.
* doc/guix.texi (Base Services): Document them.

Merge branch 'master' into staging

gnu: Add knot-service-type.

* gnu/services/dns.scm: New file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add it.
* doc/guix.texi (DNS Services): New subsubsection.

Merge branch 'master' into staging

services: openssh: Don't depend on networking.

* gnu/services/ssh.scm (openssh-shepherd-service): Drop requirement.

services: openssh: Don't depend on networking.

* gnu/services/ssh.scm (openssh-shepherd-service): Drop requirement.

services: guix: Authorize the key for bayfront.guixsd.org.

* gnu/services/base.scm (%default-authorized-guix-keys): Add
"bayfront.guixsd.org".

services: Add 'thermald-service-type'.

* gnu/services/pm.scm (<thermald-configuration>): New record type.
(thermald-shepherd-service, thermald-service-type): New variables.
* doc/guix.texi (Thermal Management): New section documenting thermald.

Merge branch 'master' into staging

services: nscd: Adjust activation snippet for /etc/resolv.conf symlinks.

Fixes <http://bugs.gnu.org/26809>.
Reported by Mark H Weaver <mhw@netris.org>.

* gnu/services/base.scm (nscd-activation): Use 'lstat' instead of
'file-exists?'.

ui: Rename '_' to 'G_'.

This avoids collisions with '_' when the latter is used as a 'match'
pattern for instance.  See
<https://lists.gnu.org/archive/html/guix-devel/2017-04/msg00464.html>.

* guix/ui.scm: Rename '_' to 'G_'.
* po/guix/Makevars (XGETTEXT_OPTIONS): Adjust accordingly.
* build-aux/compile-all.scm (warnings): Remove 'format'.
* gnu/packages.scm,
gnu/services.scm,
gnu/services/shepherd.scm,
gnu/system.scm,
gnu/system/shadow.scm,
guix/gnupg.scm,
guix/http-client.scm,
guix/import/cpan.scm,
guix/import/elpa.scm,
guix/import/pypi.scm,
guix/nar.scm,
guix/scripts.scm,
guix/scripts/archive.scm,
guix/scripts/authenticate.scm,
guix/scripts/build.scm,
guix/scripts/challenge.scm,
guix/scripts/container.scm,
guix/scripts/container/exec.scm,
guix/scripts/copy.scm,
guix/scripts/download.scm,
guix/scripts/edit.scm,
guix/scripts/environment.scm,
guix/scripts/gc.scm,
guix/scripts/graph.scm,
guix/scripts/hash.scm,
guix/scripts/import.scm,
guix/scripts/import/cpan.scm,
guix/scripts/import/cran.scm,
guix/scripts/import/crate.scm,
guix/scripts/import/elpa.scm,
guix/scripts/import/gem.scm,
guix/scripts/import/gnu.scm,
guix/scripts/import/hackage.scm,
guix/scripts/import/nix.scm,
guix/scripts/import/pypi.scm,
guix/scripts/import/stackage.scm,
guix/scripts/lint.scm,
guix/scripts/offload.scm,
guix/scripts/pack.scm,
guix/scripts/package.scm,
guix/scripts/perform-download.scm,
guix/scripts/publish.scm,
guix/scripts/pull.scm,
guix/scripts/refresh.scm,
guix/scripts/size.scm,
guix/scripts/substitute.scm,
guix/scripts/system.scm,
guix/ssh.scm,
guix/upstream.scm: Use 'G_' instead of '_'.  Most of this change was
obtained by running: "sed -i -e's/(_ "/(G_ "/g' `find -name \*.scm`".

services: herd: Make %shepherd-socket-file a parameter and export it.

* gnu/services/herd.scm (%shepherd-socket-file): Make it an exported
  parameter.
(open-connection): Adapt.

services: nscd: Create /etc/resolv.conf if it does not exist.

* gnu/services/base.scm (nscd-activation): Create /etc/resolv.conf if it
does not exist yet.

gnu: services: nginx: Fix key verification.

* gnu/services/web.scm (default-nginx-server-config): Fix wrong variable name.

gnu: services: Create logs directory.

* gnu/services/web.scm (nginx-activation): Create logs directory so nginx can
log its startup messages before it loads its configuration.