gnu: Allow a plain list of packages in 'operating-system'.

* gnu/system.scm (union): Allow (PACKAGE OUTPUT), (PACKAGE), and
  PACKAGE.
  (<operating-system>)[packages]: Make the default a list of package?
  objects.
* gnu/system/vm.scm (%demo-operating-system): Likewise.  Add a few
  packages.

gnu: Add 'inputs' field to <user-account>; make 'shell' a monadic value.

* gnu/system/shadow.scm (<user-account>)[inputs]: New field.
  (passwd-file): Bind the 'shell' field of each account.
* gnu/system/vm.scm (%demo-operating-system): Remove 'shell' field.
* gnu/system/dmd.scm (guix-build-accounts): Store a monadic value in
  'shell'.  Add 'inputs' field.
* gnu/system.scm (operating-system-derivation): Remove 'shell' field for
  'root' account.  Add all the 'user-account-inputs' to EXTRAS.

gnu: dmd: Avoid "already exists" error on startup.

* gnu/system/dmd.scm (dmd-configuration-file)[config]: Remove
  "/var/nix/gcroots/etc-directory" before trying to recreate it.

gnu: Add (gnu system).

* gnu/system/vm.scm (lower-inputs): Move to monads.scm.
  (qemu-image): Don't add GRUB-CONFIGURATION to the INPUTS-TO-COPY.
  (union, file-union, etc-directory): Move to gnu/system.scm.
  (%demo-operating-system): New variable.
  (system-qemu-image): Add 'os' parameter.  Rewrite in terms of
  'operating-system-derivation'.
* guix/monads.scm (lower-inputs): New procedure.
* gnu/system/grub.scm (grub-configuration-file): Change 'entries' to be
  a plain list instead of a list of monadic values.
* gnu/system.scm: New file.
* gnu-system.am (GNU_SYSTEM_MODULES): Add it.

gnu: Populate /etc upon startup.

* gnu/packages/patches/dmd-getpw.patch: New file.
* gnu-system.am (dist_patch_DATA): Add it.
* gnu/packages/system.scm (dmd): Use it.
* gnu/system/vm.scm (system-qemu-image): Don't explicitly populate /etc;
  don't add ETC to the GC roots.
* gnu/system/dmd.scm (dmd-configuration-file): Add 'etc' parameter.
  [config]: Populate /etc from there.

gnu: dmd: Add 'pam-services' field to <service>.

* gnu/system/dmd.scm (<service>)[pam-services]: New field.
  (mingetty-service): Add #:motd and #:allow-empty-passwords?
  parameters.  Add MOTD to 'inputs' field; add 'pam-services' field.
* gnu/system/vm.scm (system-qemu-image): Aggregate PAM entries from
  SERVICES.

gnu: vm: Fix inputs in 'file-union'.

* gnu/system/vm.scm (file-union): Filter out members of FILES that are
  outputs of INPUTS.

gnu: dmd: Add 'user-accounts' and 'user-groups' fields to <service>.

* gnu/system/shadow.scm (guix-build-accounts): Move to...
* gnu/system/dmd.scm (guix-build-accounts): ... here.
  (<service>)[user-accounts, user-groups]: New fields.
  (guix-service): New #:build-user-id and #:build-accounts parameters.
  Use 'guix-build-accounts' and set the 'user-accounts' and
  'user-groups' fields accordingly.
* gnu/system/vm.scm (system-qemu-image): Remove use of
  'guix-build-accounts'.  Augment ACCOUNTS and GROUPS from what SERVICES
  demand.

gnu: Move /etc/resolv.conf handling to the networking service.

* gnu/system/vm.scm (etc-directory): Remove 'resolv.conf'.
  (system-qemu-image): Use 'static-networking-service' with
  #:name-servers.  Don't populate the image with /etc/resolv.conf.
* gnu/system/dmd.scm (static-networking-service): Add #:name-servers
  parameter.  Use it to populate /etc/resolv.conf.

gnu: vm: Factorize /etc creation.

* gnu/system/vm.scm (expression->derivation-in-linux-vm)[lower-inputs]:
  Move to top-level...
  (lower-inputs): ... here.  New variable.
  (file-union, etc-directory): New procedures.
  (system-qemu-image): Use 'etc-directory'; remove redundant code, and
  register the result of 'etc-directory' as a GC root.

derivations: Use more keyword parameters for 'build-expression->derivation'.

* guix/derivations.scm (build-expression->derivation): Turn 'system' and
  'inputs' into keyword parameters.
  Adjust callers accordingly.
* gnu/system/linux.scm, gnu/system/vm.scm, guix/build-system/cmake.scm,
  guix/build-system/gnu.scm, guix/build-system/perl.scm,
  guix/build-system/python.scm, guix/build-system/trivial.scm,
  guix/download.scm, guix/packages.scm, guix/profiles.scm,
  guix/scripts/pull.scm, tests/derivations.scm, tests/guix-build.sh,
  tests/monads.scm, tests/store.scm, tests/union.scm: Adjust users of
  'build-expression->derivation' and 'derivation-expression'
  accordingly.
* doc/guix.texi (Derivations): Adjust 'build-expression->derivation'
  documentation accordingly.
  (The Store Monad): Likewise for 'derivation-expression'.

gnu: dmd: Update start/stop of standard service definitions.

* gnu/system/dmd.scm (mingetty-service): Add 'stop' field.
  (nscd-service): Run with '--foreground'.  Change 'stop' to use
  'make-kill-destructor'.
  (syslog-service): Run with '--no-detach'; change 'stop' similarly.
  (guix-service): Likewise for 'stop'.
  (static-networking-service): Remove 'sleep' call from 'start'.  Change
  'stop' to return #f when networking was actually stopped.

gnu: dmd: Add service documentation.

* gnu/system/dmd.scm (<service>): Add 'documentation' field.
  (host-name-service, mingetty-service, nscd-service, syslog-service,
  static-networking-service): Provide a 'documentation' value.
  (dmd-configuration-file): Use it.

Merge branch 'master' into core-updates

Conflicts:
	guix/packages.scm

gnu: vm: Really create a QCOW2-format image.

* gnu/system/vm.scm (expression->derivation-in-linux-vm): Pass "-f
  qcow2" to 'qemu-img create'.

gnu: vm: Rewrite helper functions as monadic functions.

* gnu/system/dmd.scm (host-name-service, nscd-service, mingetty-service,
  syslog-service, guix-service, static-networking-service): Rewrite as
  monadic functions.
  (dmd-configuration-file): Use 'text-file' instead of
  'add-text-to-store'.
* gnu/system/grub.scm (grub-configuration-file): Rewrite as a monadic
  function.
* gnu/system/linux.scm (pam-services->directory): Likewise.
* gnu/system/shadow.scm (group-file, passwd-file, guix-build-accounts):
  Likewise.
* gnu/system/vm.scm (expression->derivation-in-linux-vm, qemu-image,
  union, system-qemu-image): Likewise.

gnu: guix: Update to 0.4.

* gnu/packages/package-management.scm (guix): Update to 0.4.
  (guix-0.4): Remove.
* gnu/system/vm.scm (qemu-image, system-qemu-image): Use GUIX instead of
  GUIX-0.4.

gnu: vm: Remove erroneous store reference.

* gnu/system/vm.scm (system-qemu-image): Remove reference from BOOT to
  MINGETTY since MINGETTY may not be valid yet.

gnu: vm: Add more packages to the profile.

* gnu/system/vm.scm (system-qemu-image): Add grep, sed, and Findutils to
  the profile.

gnu: vm: Add a few packages to the default profile.

* gnu/system/vm.scm (system-qemu-image): Add procps, psmisc, and Zile to
  the default profile.  Increase the image size to 550 MiB.