services: Add 'console-font-service'.

* gnu/services/base.scm (unicode-start, console-font-service): New
  procedures.
  (%base-services): Call 'console-font-service' for TTY1 to TTY6.
* gnu/system/install.scm (installation-services): Add comment about the
  console font.  Call 'console-font-service' for TTY1 to TTY6.

services: syslog: Don't write trivial error messages to /dev/console.

* gnu/services/base.scm (syslog-service): Change "*.err" to "*.alert".

services: Add options to 'guix-service'.

* gnu/services/base.scm (guix-service): Add #:use-substitutes? and
  #:extra-options parameters, and honor them.
* doc/guix.texi (Base Services): Adjust accordingly.

services: Add Tor service.

* gnu/services/networking.scm (tor-service): New procedure.
* doc/guix.texi (Networking Services): Document it.
* build-aux/hydra/demo-os.scm: Use it.  Add TOR and TORSOCKS to
  'packages'.

services: networking: Set interfaces up; delete default route only when needed.

* gnu/services/networking.scm (static-networking-service): Use -i, -A,
  and --up with Inetutils' ifconfig.  Do 'route del -net default' only
  when GATEWAY is true.

services: Provide a 'loopback' service by default.

* gnu/services/networking.scm (static-networking-service): Add
  #:provision parameter; use it.
* gnu/services/base.scm (%base-services): Call
  'static-networking-service' for "lo".

services: Use more Texinfo markup in docstrings.

* gnu/services/base.scm (host-name-service): Use Texinfo markup.
  (mingetty-service): Comment on #:allow-empty-passwords?.  Improve
  markup.
  (syslog-service, guix-service): Use Texinfo markup.
* gnu/services/networking.scm (static-networking-service): Likewise.
* gnu/services/xorg.scm (slim-service): Likewise.

services: udev: Improve synchronization when starting.

* gnu/services/base.scm (udev-service)[start]: Add 'wait-for-udevd', and
  call it before running 'udevadm trigger'.  Pass --action=add to
  'udevadm trigger'.  Call 'udevadm settle' after 'udevadm trigger'.

services: xorg: Remove optional sections from xorg.conf.

* gnu/services/xorg.scm (xorg-start-command)[xserver.conf]: Remove
  sections "Monitor", "InputClass", "ServerLayout", "Device", and
  "Screen".

services: xorg: Require 'udev'.

* gnu/services/xorg.scm: Add 'udev' to the 'requirement' field.

services: xorg: Add drivers to the default search path.

* gnu/services/xorg.scm (xorg-start-command)[xserver.conf]: Add
  'ModulePath' entries for xf86-video-{fbdev,cirrus,intel,mach64,nv} and
  xf86-input-{synaptics,vmmouse}.

services: xorg: Fix typo in font path.

* gnu/services/xorg.scm (xorg-start-command)[xserver.conf]: Fix typo in
  font path.

services: Update to use the dmd 0.2 API.

* gnu/services/avahi.scm (avahi-service)[start]: Wrap command in a
  list.
* gnu/services/dbus.scm (dbus-service)[start]: Likewise.
* gnu/services/ssh.scm (lsh-service): Likewise.
* gnu/services/base.scm (mingetty-service)[start]: Likewise.
  (nscd-service)[start]: Likewise.
  (syslog-service)[start]: Likewise.
  (guix-service)[start]: Likewise.
  (udev-service)[start]: Use 'exec-command' instead of 'execl'.
* gnu/services/xorg.scm (slim-service)[start]: Likewise, and use
  #:environment-variables.

services: Add lshd service.

* gnu/services/ssh.scm: New file.
* gnu-system.am (GNU_SYSTEM_MODULES): Add it.

services: udev: Make sure modules are found, and use "udevadm settle".

* gnu/services/base.scm (udev-service): Set $LINUX_MODULE_DIRECTORY.  In
  the parent, invoke "udevadm settle" before "udevadm trigger".

system: Add a 'system?' field to user accounts.

* gnu/system/shadow.scm (<user-account>)[system?]: New field.
* gnu/system.scm (user-account->gexp): Add it.
* guix/build/activation.scm (add-user): Add #:system? parameter and
  honor it.
  (activate-users+groups): Handle the 'system?' part of user tuples.
  Pass it to 'add-user'.  Don't create PROFILE-DIR when SYSTEM? is
  true.
* gnu/services/dbus.scm (dbus-service): Add 'system?' field for
  "messagebus" account.
* gnu/services/base.scm (guix-build-accounts): Likewise.
* gnu/services/avahi.scm (avahi-service): Likewise.

services: Add udev service, and add it to '%base-services'.

* gnu/services/base.scm (udev-service): New procedure.
  (%base-services): Use it.
* gnu/system.scm (%base-packages): Add UDEV.

system: Remove useless 'members' field of 'user-group'.

* gnu/system/shadow.scm (<user-group>)[members]: Remove field.
* gnu/system/install.scm (installation-os)[users]: Remove 'members'
  fields.  Use 'supplementary-groups' for 'guest'.
* build-aux/hydra/demo-os.scm (users): Likewise.
* gnu/services/base.scm (guix-service): Remove 'members' field.

Merge branch 'master' into core-updates

services: Use a fixed GID for the build group and use that for the store.

This partly reverts commit 185f669 ("services: Make sure the store's
group is the build group.")

* gnu/services/base.scm (guix-service)[activate]: Remove 'chown' call.
  Add 'id' field to 'user-group' form.
* guix/build/install.scm (directives): Set the store's GID to 30000.