nls: Add German translation.

nls: Update eo, pt_BR, sr, and vi package translations.

Merge branch 'bug-17853'

guix system: Fix return value for 'reconfigure'.

* guix/scripts/system.scm (perform-action) <reconfigure>: Add missing
  'return' expression.

linux-initrd: Allow extra modules to be passed to 'base-initrd'.

* gnu/system/linux-initrd.scm (base-initrd): Add #:extra-modules
  parameter.

install: Make /var/db and /mnt.

* guix/build/install.scm (directives): Add /var/db and /mnt.

guix system: Convert to monadic style.

* guix/scripts/system.scm (references*, topologically-sorted*,
  show-what-to-build*): New procedures.
  (copy-closure): Turn into a monadic procedure.
  (install): Likewise, and adjust parameter list.
  (switch-to-system): Likewise.
  (system-derivation-for-action, grub.cfg, maybe-build, perform-action):
  New procedures.
  (guix-system): Use them.

vm: Add support for i686.

Partially fixes <http://bugs.gnu.org/18002>.
Reported by David Thompson <dthompson2@worcester.edu>.

* guix/build/vm.scm (qemu-command): Add optional 'system' parameter.
  Special-case "^i[3456]86$".
* gnu/system/vm.scm (system-qemu-image/shared-store-script): Use it.

gnu: Add chess and xboard.

* gnu/packages/games.scm (xboard, chess): New variables.

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.

system: Add 'which' to the base packages.

* gnu/system.scm (%base-packages): Add WHICH.

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".

system: Remove erroneous system binding in profile maker.

Partly fixes <http://bugs.gnu.org/18002>.
Reported by David Thompson <dthompson2@worcester.edu>.

* gnu/system.scm (union): Remove #:system parameter, which was unused.

gexp: Resolve the default system at '>>=' time.

Partly fixes <http://bugs.gnu.org/18002>.
Reported by David Thompson <dthompson2@worcester.edu>.

* guix/gexp.scm (gexp->derivation): Change #:system to default #f.
  Use (%current-system) from within the 'mlet*'.
* tests/gexp.scm ("gexp->derivation, default system"): New test.

monads: Fix 'mapm' so that effects happen from left to right.

* guix/monads.scm (mapm): Don't reverse LST, so that items are processed
  from left to right.  Bind the result of 'foldm' and reverse it.
* tests/monads.scm ("sequence"): Change 'frob' so it performs its side
  effect within an 'mlet' body.  Adjust call accordingly.

gnu: Add links.

* gnu-system.am (GNU_SYSTEM_MODULES): Add new file.
* gnu/packages/links.scm: New file.

doc: Start writing about services.

* doc/guix.texi (Using the Configuration System): Remove details about
  '%base-services', and link to "Services".
  (Services): Add introductory text.
  (Base Services, Networking Services, X Window): New nodes.

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.

system: Allow root to use 'groupadd' & co. without authenticating.

This fixes a bug whereby, if #:allow-root-passwords was #f, 'groupadd'
would ask for a password.  This is particularly problematic during
activation.

* gnu/system/linux.scm (rootok-pam-service): New procedure.
  (base-pam-services): Use it for all the user* and group* commands.