gnu: Split (gnu packages base), adding (gnu packages commencement).

* gnu/packages/base.scm (gnu-make-boot0, diffutils-boot0,
  findutils-boot0, %boot0-inputs, nix-system->gnu-triplet, boot-triplet,
  binutils-boot0, gcc-boot0, perl-boot0, linux-libre-headers-boot0,
  texinfo-boot0, %boot1-inputs, glibc-final-with-bootstrap-bash,
  cross-gcc-wrapper, static-bash-for-glibc, glibc-final,
  gcc-boot0-wrapped, %boot2-inputs, binutils-final, libstdc++,
  gcc-final, ld-wrapper-boot3, %boot3-inputs, bash-final, %boot4-inputs,
  guile-final, gnu-make-final, ld-wrapper, coreutils-final, grep-final,
  %boot5-inputs, %final-inputs, canonical-package, gcc-toolchain,
  gcc-toolchain-4.8, gcc-toolchain-4.9): Move to...
* gnu/packages/commencement.scm: ... here.  New file.
* gnu-system.am (GNU_SYSTEM_MODULES): Add it.
* build-aux/check-final-inputs-self-contained.scm: Adjust accordingly.
* gnu/packages/cross-base.scm: Likewise.
* gnu/packages/make-bootstrap.scm: Likewise.
* guix/build-system/cmake.scm (cmake-build): Likewise.
* guix/build-system/gnu.scm (standard-packages, gnu-build,
  gnu-cross-build): Likewise.
* guix/build-system/perl.scm (perl-build): Likewise.
* guix/build-system/python.scm (python-build): Likewise.
* guix/build-system/trivial.scm (guile-for-build): Likewise.
* guix/download.scm (url-fetch): Likewise.
* guix/gexp.scm (default-guile): Likewise.
* guix/git-download.scm (git-fetch): Likewise.
* guix/monads.scm (run-with-store): Likewise.
* guix/packages.scm (default-guile): Likewise.
* guix/scripts/package.scm (guix-package): Likewise.
* guix/scripts/refresh.scm: Likewise.
* guix/svn-download.scm (svn-fetch): Likewise.
* tests/builders.scm (%bootstrap-inputs, %bootstrap-search-paths):
  Likewise.
* tests/packages.scm ("GNU Make, bootstrap"): Likewise.
* tests/guix-package.sh: Likewise.
* gnu/services/base.scm: Use 'canonical-package' instead of xxx-final.
* gnu/services/xorg.scm: Likewise.
* gnu/system/vm.scm: Likewise.
* guix/scripts/pull.scm (guix-pull): Likewise.

services: lsh: Fix activation script.

* gnu/services/ssh.scm (lsh-service)[activate]: Import (guix build utils)
  for 'mkdir-p'.

services: Use system groups where applicable.

* gnu/services/avahi.scm (avahi-service): Add 'system?' field to
  'user-group' form.
* gnu/services/base.scm (guix-service): Likewise.
* gnu/services/dbus.scm (dbus-service): Likewise.
* gnu/services/networking.scm (tor-service): Likewise.

services: xorg: Honor ~/.xsession.

* gnu/services/xorg.scm (xinitrc): Attempt to execute ~/.xsession.

services: xorg: Remove /var/run/slim.lock when starting.

Reported by Mark H. Weaver.

* gnu/services/xorg.scm (slim-service)[start]: Remove /var/run/slim.lock
  before starting 'slim'.

install: Add a service to back the store with the target disk.

Fixes <http://bugs.gnu.org/18061>.
Reported by Adam Pribyl <pribyl@lowlevel.cz>.

* gnu/services/dmd.scm (dmd-configuration-file)[config]: Import (guix
  build utils).
* gnu/system/install.scm (make-cow-store, cow-store-service): New
  procedures.
  (installation-services): Use it.
  (%backing-directory): New variable.
* doc/guix.texi (System Installation): Add the 'deco start cow-store
  /mnt' phase.

system: Recognize more file system flags.

* guix/build/linux-initrd.scm (MS_NOSUID, MS_NODEV, MS_NOEXEC): New
  variables.
  (mount-flags->bit-mask): New procedure.
  (mount-file-system)[flags->bit-mask]: Remove.
  Use 'mount-flags->bit-mask' instead.
  In /etc/mtab, use the empty string when OPTIONS is false.
* gnu/services/base.scm (file-system-service): Add #:flags parameter and
  honor it.
* gnu/system.scm (other-file-system-services): Pass FLAGS to
  'file-system-service'.

system: Add 'file-system' decl. for /dev/pts, and use the right options.

Fixes <http://bugs.gnu.org/18081>.

* gnu/system/file-systems.scm (%devtmpfs-file-system): Add
  'needed-for-boot?' field.
  (%tty-gid, %pseudo-terminal-file-system): New variables.
  (%base-file-systems): Add %PSEUDO-TERMINAL-FILE-SYSTEM.
* gnu/services/base.scm (udev-service): Remove dependency on
  'file-system-/dev'.
* gnu/system/shadow.scm (%base-groups): Add 'id' field for group 'tty'.
* guix/build/linux-initrd.scm (boot-system): Remove 'mount' call for
  /dev/pts.
* doc/guix.texi (File Systems): Add %pseudo-terminal-file-system.

system: Add 'create-mount-point?' file system option.

* gnu/system/file-systems.scm (<file-system>)[create-mount-point?]: New
  field.
* gnu/services/base.scm (file-system-service): Add #:create-mount-point?
  parameter and honor it.
* gnu/system.scm (other-file-system-services): Update
  'file-system-service' call accordingly.
* doc/guix.texi (File Systems): Document it.

system: Add '%devtmpfs-file-system' for udev, and '%base-file-systems'.

Suggested by Adam Pribyl <pribyl@lowlevel.cz>.

* gnu/services/base.scm (udev-service)[requirement]: Add
  'file-system-/dev'.
* gnu/system/file-systems.scm (%devtmpfs-file-system,
  %base-file-systems): New variables.
* gnu/system/install.scm (installation-services)[file-systems]: Use
  %base-file-systems.
* build-aux/hydra/demo-os.scm (file-systems): Likewise.
* doc/guix.texi (System Installation): Show %BASE-FILE-SYSTEMS in the
  example.
  (Using the Configuration System): Likewise.
  (File Systems): Document %base-file-systems, %devtmpfs-file-system,
  %binary-format-file-system, and %fuse-control-file-system.

services: Allow 'check-file-system' to work for non-boot-time file systems.

* gnu/services/base.scm (file-system-service)[start]: Set $PATH so that
  fsck.* can be found.  Reported by "DusXMT".

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".