* guix/scripts/graph.scm (%options, show-help): Add '--expression'.
  (guix-graph): Call 'read/eval-package-expression' for 'expression'
  pairs in OPTS.
* tests/guix-graph.sh: Add tests.
* doc/guix.texi (Invoking guix graph): Document it.

* doc/guix.texi (Desktop Services): Add polkit-service and
  elogind-service documentation.

* gnu/services/desktop.scm (polkit-service): New function.
  (%desktop-services): Add polkit service.

* gnu/packages/polkit.scm (polkit): Configure to look for actions and
  rules in the system profile.  Arrange to look for the setuid helper in
  /run/setuid-programs.  Fix introspection installation.

Based on a patch by Mark H Weaver <mhw@netris.org>.

* gnu/packages/polkit.scm (polkit): Depend on elogind.

* gnu/services/desktop.scm (<elogind-configuration>): New record type.
  (elogind-configuration-file, elogind-service): New functions.
  (%desktop-services): Add elogind-service.

* gnu/packages/freedesktop.scm (elogind): Update to 219.12.  Use a tarball
  instead of a git checkout.

* gnu/packages/backup.scm (attic): New variable.

Signed-off-by: Alex Kost <alezost@gmail.com>

* gnu/packages/python.scm (python-msgpack, python2-msgpack): New variables.

Signed-off-by: Alex Kost <alezost@gmail.com>

* gnu/packages/python.scm (python-llfuse, python2-llfuse): New variables.

Signed-off-by: Alex Kost <alezost@gmail.com>

* gnu/packages/emacs.scm (flycheck): Change version to 0.23.
  Replace MELPA tarball with the upstream release.

* emacs/guix-command.el (guix-command-improve-import-argument): New
  variable and function.
  (guix-command-argument-improvers): Add it.

* gnu/packages/xfce.scm (xfce)[propagated-inputs]: Add xfce4-pulseaudio-plugin.

* gnu/packages/xfce.scm (xfce4-pulseaudio-plugin): New variable.

* gnu/packages/xfce.scm (xfce4-panel)[arguments]: New field.

* gnu/packages/xfce.scm (libxfce4ui)[propagated-inputs]: Add gtk+.

* gnu/packages/bioinformatics.scm (deeptools): New variable.

* gnu/packages/perl.scm (perl-czplib): New variable.

This patch should have been added in cdd383e9.

* gnu/packages/patches/guile-present-coding.patch: New file.
* gnu-system.am (dist_patch_DATA): Add it.

* gnu/packages/music.scm (zynaddsubfx): New variable.

* gnu/packages/xml.scm (minixml): New variable.

* gnu/packages/engineering.scm (gerbv): New variable.

* gnu/packages/gettext.scm (po4a): New variable.

* gnu/packages/fonts.scm (font-tex-gyre): New variable.

* guix/licenses.scm (gfl1.0): New variable.

* guix/import/gem.scm (make-gem-sexp): Properly handle an empty list of
  licenses.  When rendering a list of licenses, cons 'list onto the front of
  the expression.
* tests/gem.scm: New file.
* Makefile.am (SCM_TESTS): Add it.

* gnu/packages/web.scm (sassc): New variable.

* gnu/packages/openstack.scm (python-oslotest, python2-olsotest): New variables.

* gnu/packages/openstack.scm (python-os-client-config,
  python2-os-client-config): New variables.

* gnu/packages/openstack.scm (python-mox3, python2-mox3): New variables.

* gnu/packages/openstack.scm: New file.
* gnu-system.am: Add it.

* gnu/packages/python.scm (python-appdirs, python2-appdirs): New variables.

* gnu/packages/ssh.scm (guile-ssh): Update to 0.8.0.
  [inputs]: Use LIBGCRYPT instead of LIBGCRYPT-1.5.

* gnu/packages/ssh.scm (libssh): Update to 0.6.5.
  [source]: Remove 'patches'.
  [inputs]: Use LIBGCRYPT instead of LIBGCRYPT-1.5.

* gnu/packages/emacs.scm (flycheck): New variable.

* gnu/packages/emacs.scm (let-alist): New variable.

* emacs/guix-command.el: Require 'guix-external'.
  (guix-run-view-graph): New function.
  (guix-command-additional-execute-arguments,
  guix-command-special-executors): Add entries for "View graph" action.

* emacs/guix-utils.el (guix-find-file-function): New variable.
  (guix-find-file): Use it.

* emacs/guix-external.el: New file.
* emacs.am (ELFILES): Add it.

* emacs/guix-main.scm: Use (ice-9 popen) module.
  (pipe-guix-output): New procedure.