gnu: ddrescue: Update to 1.20.

* gnu/packages/disk.scm (ddrescue): Update to 1.20.

gnu: sipwitch: Update to 1.9.10.

* gnu/packages/telephony.scm (sipwitch): Update to 1.9.10.

gnu: ucommon: Update to 6.6.0.

* gnu/packages/telephony.scm (ucommon): Update to 6.6.0.

gnu: parallel: Update to 20150922.

* gnu/packages/parallel.scm (parallel): Update to 20150922.

gnu: xapian: Update to 1.2.21.

* gnu/packages/search.scm (xapian): Update to 1.2.21.

emacs: devel: Highlight 'modify-phases' keywords.

* emacs/guix-guile.el (guix-guile-keyword-regexp): New function.
* emacs/guix-devel.el (guix-devel-faces): New custom group.
  (guix-devel-modify-phases-keyword): New face.
  (guix-devel-modify-phases-keyword-regexp,
  guix-devel-font-lock-keywords): New variables.
  (guix-devel-modify-phases-font-lock-matcher,
  guix-devel-modify-phases-font-lock-pre): New functions.
  (guix-devel-mode): Adjust to add/remove font-lock-keywords.

gnu: mu: Update to 0.9.13.

* gnu/packages/mail.scm (mu): Update to 0.9.13.

gnu: ncmpcpp: Update to 0.6.7.

* gnu/packages/mpd.scm (ncmpcpp): Update to 0.6.7.

gnu: qemu: Update to 2.4.0.1.  Include fix for CVE-2015-6855.

* gnu/packages/patches/qemu-CVE-2015-3209.patch,
  gnu/packages/patches/qemu-CVE-2015-4037.patch,
  gnu/packages/patches/qemu-CVE-2015-4103.patch,
  gnu/packages/patches/qemu-CVE-2015-4104.patch,
  gnu/packages/patches/qemu-CVE-2015-4105.patch,
  gnu/packages/patches/qemu-CVE-2015-4106-pt1.patch,
  gnu/packages/patches/qemu-CVE-2015-4106-pt2.patch,
  gnu/packages/patches/qemu-CVE-2015-4106-pt3.patch,
  gnu/packages/patches/qemu-CVE-2015-4106-pt4.patch,
  gnu/packages/patches/qemu-CVE-2015-4106-pt5.patch,
  gnu/packages/patches/qemu-CVE-2015-4106-pt6.patch,
  gnu/packages/patches/qemu-CVE-2015-4106-pt7.patch,
  gnu/packages/patches/qemu-CVE-2015-4106-pt8.patch,
  gnu/packages/patches/qemu-CVE-2015-5745.patch: Delete files.
* gnu/packages/patches/qemu-CVE-2015-6855.patch: New file.
* gnu-system.am (dist_patch_DATA): Add the new patch and delete the old ones.
* gnu/packages/qemu.scm (qemu-headless): Update to 2.4.0.1.  Add the new patch
  and delete the old ones.

Merge branch 'core-updates'

lint: Improve 'check-texinfo-markup'.

* guix/scripts/lint.scm (check-description-style): Set 'field' parameter
  when emitting a warning in 'check-texinfo-markup'.  Catch any error
  that may occur in during the 'texi->plain-text' conversion.  This is a
  followup to commit 2748ee3.

gnu: ibus: Add input gtk+-3.

* gnu/packages/ibus.scm (ibus)[inputs]: Add the required gtk+-3.

http-client: Backport Guile fix for 'read-chunk-header'.

Fixes the wrong-type-arg exception initially reported
at <http://debbugs.gnu.org/cgi/bugreport.cgi?bug=19976#5>
by Ricardo Wurmus <rekado@elephly.net>.

* guix/http-client.scm (read-chunk-header): Backport Guile commit 53b8d5f.

gnu: Add squashfs-tools.

* gnu/packages/compression.scm (squashfs-tools): New variable.

offload: Use gzip instead of xz for compression on the master.

* guix/scripts/offload.scm (send-files): Use gzip --fast instead of xz.

utils: Add #:options parameter for compression output ports.

* guix/utils.scm (compressed-output-port,
  call-with-compressed-output-port): Add #:options parameter and honor
  it.

gnu: Add Gajim.

* gnu/packages/messaging.scm (gajim): New variable.

gnu: Add python-nbxmpp.

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

gnu: Add python-gnupg.

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

gnu: Add pyOpenSSL.

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