doc: Fix typos.

* doc/guix.texi (Build Systems)[ocaml-build-system]: Fix typo.
(Log Rotation)[periodic-rotations]: ditto.
(Database Services)[redis-service-type]: ditto.
(OpenSMTPD Service)[opensmtpd-configuration]: ditto.
(VPN Services)[OpenVPN]: ditto.
(Power management Services)[tlp-configuration]: ditto.
(Git daemon service)[git-daemon-service]: ditto.
(Running GuixSD in a VM): ditto.
* gnu/services/pm.scm (tlp-configuration)[runtime-pm-blacklist]: Fix typo.
* gnu/services/vpn.scm (openvpn-client-configuration)[status]: ditto.

tests: Add GNU dicod test.

* gnu/tests/dict.scm: New file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add it.

tests: Introduce 'simple-operating-system' and use it.

* gnu/tests.scm (%simple-os): New macro.
(simple-operating-system): New macro.
* gnu/tests/base.scm (%simple-os): Define using 'simple-operating-system'.
(%mcron-os): Use 'simple-operating-system'.
* gnu/tests/mail.scm (%opensmtpd-os): Likewise.
* gnu/tests/messaging.scm (%base-os, os-with-service): Remove.
(run-xmpp-test): Use 'simple-operating-system'.
* gnu/tests/networking.scm (%inetd-os): Likewise.
* gnu/tests/ssh.scm (%base-os, os-with-service): Remove.
(run-ssh-test): Use 'simple-operating-system'.
* gnu/tests/web.scm (%nginx-os): Likewise.

services: dicod: Allow the configuration of "handlers".

* gnu/services/dict.scm (<dicod-configuration>)[handlers]: New field.
(<dicod-handler>): New record type.
(<dicod-database>): Add fields.
(dicod-configuration-file): Support convert handlers and enhanced databases.
configuration to config file.
* doc/guix.texi (Miscellaneous Services): Update accordingly.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

gnu: linux-libre: Update to 4.10.8 [fixes CVE-2017-7184].

* gnu/packages/linux.scm (%linux-libre-version): Update to 4.10.8.
(%linux-libre-hash): Update hash.

gnu: linux-libre@4.9: Update to 4.9.20 [fixes CVE-2017-7184].

* gnu/packages/linux.scm (linux-libre-4.9): Update to 4.9.20.

gnu: linux-libre@4.4: Update to 4.4.59 [fixes CVE-2017-7184].

* gnu/packages/linux.scm (linux-libre-4.4): Update to 4.4.59.

gnu: guile-opengl: Build with Guile 2.2.

* gnu/packages/gl.scm (guile-opengl): Build with Guile 2.2.

gnu: libtermkey: Update to 0.20.

gnu/packages/terminals.scm (libtermkey): Update to 0.20.

substitute: Send ‘User-Agent’ header.

* guix/scripts/substitute.scm (narinfo-request): Pass ‘User-Agent’ #:headers
to ‘build-request’.

gnu: xonsh: Update to 0.5.9.

* gnu/packages/shells.scm (xonsh): Update to 0.5.9.

gnu: parallel: Update to 20170322.

* gnu/packages/parallel.scm (parallel): Update to 20170322.

gnu: tiled: Update to 0.18.2.

* gnu/packages/game-development.scm (tiled): Update to 0.18.2.

gnu: nano: Update to 2.8.0.

* gnu/packages/nano.scm (nano): Update to 2.8.0.

gnu: hdparm: Use ‘modify-phases’ syntax.

* gnu/packages/linux.scm (hdparm): Use ‘modify-phases’.

gnu: hdparm: Expand synopsis and description.

* gnu/packages/linux.scm (hdparm)[synopsis, description]: Add some more
common uses, more examples, and more objective information.

gnu: hdparm: Update to 9.51.

* gnu/packages/linux.scm (hdparm): Update to 9.51.

gnu: goffice: Update to 0.10.34.

* gnu/packages/gnome.scm (goffice): Update to 0.10.34.

gnu: gmime: Update to 2.6.23.

* gnu/packages/mail.scm (gmime): Update to 2.6.23.

gnu: freedoom: Update to 0.11.2.

* gnu/packages/games.scm (freedoom): Update to 0.11.2.