doc: Add services to the configuration template.

* gnu/system/os-config.tmpl (services): New field.

install: Make sure 'info' can decompress the Info files.

* gnu/system/install.scm (log-to-info): Add GZIP to $PATH.

system: Add "en_US.UTF-8" to the default locales, for backward compatibility.

* gnu/system/locale.scm (%default-locale-definitions): Add
  "en_US.UTF-8".

monads: Move '%store-monad' and related procedures where they belong.

This turns (guix monads) into a generic module for monads, and moves the
store monad and related monadic procedures in their corresponding
module.

* guix/monads.scm (store-return, store-bind, %store-monad, store-lift,
  text-file, interned-file, package-file, package->derivation,
  package->cross-derivation, origin->derivation, imported-modules,
  compiled, modules, built-derivations, run-with-store): Move to...
* guix/store.scm (store-return, store-bind, %store-monad, store-lift,
  text-file, interned-file): ... here.
  (%guile-for-build): New variable.
  (run-with-store): Moved from monads.scm.  Remove default value for
  #:guile-for-build.
* guix/packages.scm (default-guile): Export.
  (set-guile-for-build): New procedure.
  (package-file, package->derivation, package->cross-derivation,
  origin->derivation): Moved from monads.scm.
* guix/derivations.scm (%guile-for-build): Remove.
  (imported-modules): Rename to...
  (%imported-modules): ... this.
  (compiled-modules): Rename to...
  (%compiled-modules): ... this.
  (built-derivations, imported-modules, compiled-modules): New
  procedures.
* gnu/services/avahi.scm, gnu/services/base.scm, gnu/services/dbus.scm,
  gnu/services/dmd.scm, gnu/services/networking.scm,
  gnu/services/ssh.scm, gnu/services/xorg.scm, gnu/system/install.scm,
  gnu/system/linux-initrd.scm, gnu/system/shadow.scm, guix/download.scm,
  guix/gexp.scm, guix/git-download.scm, guix/profiles.scm,
  guix/svn-download.scm, tests/monads.scm: Adjust imports accordingly.
* guix/monad-repl.scm (default-guile-derivation): New procedure.
  (store-monad-language, run-in-store): Use it.
* build-aux/hydra/gnu-system.scm (qemu-jobs): Add explicit
  'set-guile-for-build' call.
* guix/scripts/archive.scm (derivation-from-expression): Likewise.
* guix/scripts/build.scm (options/resolve-packages): Likewise.
* guix/scripts/environment.scm (guix-environment): Likewise.
* guix/scripts/system.scm (guix-system): Likewise.
* doc/guix.texi (The Store Monad): Adjust module names accordingly.

Merge branch 'master' into core-updates

install: Use a low-memory nscd caching policy.

* gnu/system/install.scm (%nscd-minimal-caches): New variable.
  (installation-services): Use as 'nscd-service' argument.

Merge branch 'master' into 'core-updates'.

system: grub: Make sure the font and background image are always found.

* gnu/system/grub.scm (eye-candy): Add 'search --file --set'.

system: Adjust 'grub.cfg' to work on systems with a separate /boot.

Fixes <http://bugs.gnu.org/19220>.
Reported by Nikita Karetnikov <nikita@karetnikov.org>.

* gnu/system/grub.scm (grub-configuration-file)[entry->gexp]: Add
  'search --file --set'.
  (grub-configuration-file)[builder]: Remove 'search.file'.

vm: Use QEMU's standard VGA emulation by default.

* gnu/system/vm.scm (common-qemu-options): Add "-vga std".

system: Add skeleton '.zlogin'.

* gnu/system/shadow.scm (default-skeletons): Add .zlogin.

system: Cleanup bash startup files.

* gnu/system.scm (etc-directory) (bashrc): Rename to 'profile'.
* gnu/system/shadow.scm (default-skeletons): Rename '.bashrc' to
  '.bash_profile'. Don't source /etc/profile.

linux-initrd: Add the 'virtio_console' module for QEMU guests.

* gnu/system/linux-initrd.scm (base-initrd)[virtio-modules]: Add
  "virtio_console".

Revert "system: Add a 'needed-for-boot?' field to 'mapped-device'."

This reverts commit 3b09332adf7ce8e976a4d117a62c586a53af04aa, which
turned out to be a bad idea because we need to have dependency
information between the device-mapping service and the file-system
service that uses it.

system: locale: Fix typo in docstring.

* gnu/system/locale.scm (localedef-command): Fix typo.

system: Add a 'needed-for-boot?' field to 'mapped-device'.

* gnu/system/file-systems.scm (<mapped-device>)[needed-for-boot?]: New
  field.
* gnu/system.scm (operating-system-user-mapped-devices,
  operating-system-boot-mapped-devices): Use it instead of trying to
  guess.  Guessing doesn't work when one refers to a partition using its
  label, for instance.
* doc/guix.texi (Mapped Devices): Document 'needed-for-boot?'.

system: Change "en_US.UTF-8" to "en_US.utf8".

* build-aux/hydra/demo-os.scm (locale): Change to "en_US.utf8".
* gnu/system/install.scm (installation-os)[locale]: Ditto.

linux-initrd: Remove the ".ko" suffix from module names in 'base-initrd'.

* gnu/system/linux-initrd.scm (base-initrd): Remove the .ko suffix from
  module names.

linux-initrd: Remove now redundant module names.

* gnu/system/linux-initrd.scm (base-initrd)[virtio-modules]: Remove
  "virtio.ko" and "virtio_ring.ko".
  [virtio-9p-modules]: Remove "fscache.ko" and "9pnet.ko".
  [linux-modules]: Remove "libahci.ko".

linux-boot: Load modules and their dependencies, à la 'modprobe'.

* gnu/build/linux-boot.scm: Use (gnu build linux-modules).
  (load-linux-module*): Remove.
  (boot-system): Add #:linux-module-directory parameter.
  [lookup-module]: New procedure.
  Call 'current-module-debugging-port'.  Pass #:lookup-module to
  'load-linux-module*'.  Map LOOKUP-MODULE on LINUX-MODULES.
* gnu/system/linux-initrd.scm (base-initrd): Adjust 'boot-system' call
  accordingly.  Adjust #:modules argument as well.
* gnu/system.scm (operating-system-activation-script)[%modules]: Likewise.
* gnu/system/vm.scm (expression->derivation-in-linux-vm): Likewise.