Reported by Mark H Weaver <mhw@netris.org>

* guix/build/glib-or-gtk-build-system.scm (generate-icon-cache): Add check for
  existence of icons directory.

* gnu/packages/linux.scm (iw): New variable.

* gnu/packages/linux.scm (libnl): Update to 3.2.25.

* guix/monads.scm (lower-inputs, derivation-expression): Remove.
* tests/monads.scm (derivation-expression, "mlet* +
  derivation-expression"): Remove.

* guix/monads.scm (text-file*): Move to...
* guix/gexp.scm (text-file*): ... here.  Rewrite using gexps.
* tests/monads.scm ("text-file*"): Move to...
* tests/gexp.scm ("text-file*"): ... here.

* gnu/services/base.scm (user-processes-service): Write "sending all
  processes..." message to the current output port, not to /dev/console.

* gnu/packages/xlockmore.scm: Remove.
* gnu/packages/xdisorg.scm (xlockmore): New variable, from
  xlockmore.scm.
* gnu-system.am (GNU_SYSTEM_MODULES): Remove xlockmore.scm.

* gnu/packages/xlockmore.scm (xlockmore): Update to 5.45.
  [arguments]: Add #:configure-flags.

* gnu/packages/gnome.scm (evince): Add 'dconf' and 'libcanberra' inputs.
  Remove custom phase 'set-mime-search-path which is now handled by
  glib-or-gtk-build-system.

* gnu/packages/libcanberra.scm (libcanberra): Add input
  'sound-theme-freedesktop'.  Add "libcanberra-sound-theme-freedesktop.patch"
  and related phase 'patch-default-sounds-directory to patch the default
  sounds directory.

* gnu/packages/gnome.scm (dconf): New variable.

* guix/build/glib-or-gtk-build-system.scm (data-directories): Rename
  'schemas-directories' to 'data-directories' and add support for XDG theming
  data.

* guix/build/glib-or-gtk-build-system.scm (gio-module-directories): New
  function.

* guix/build/glib-or-gtk-build-system.scm (wrap-all-programs): Update names to
  reflect that we are dealing with more types of data and not only with
  schemas.  Add handling of GIO modules.

* guix/build-system/glib-or-gtk.scm (lower): Import the 'bin' output of GLib
  instead of 'out'.  This was an error since we need the program
  'glib-compile-schemas'.  Update the description.

* gnu/packages/video.scm (ffmpeg): Update to version 2.5.3.

* gnu/packages/video.scm (ffmpeg-2.2): Update to version 2.2.11.

* gnu/packages/algebra.scm (gp2c): Update to 0.0.9pl2.

* gnu/packages/algebra.scm (pari-gp): Update to 2.7.2.

* guix/derivations.scm (substitution-oracle): Use sets instead of lists.

This yields a 46% improvement in 'derivation-prerequisites' invocations
on the Emacs derivation.

* guix/derivations.scm (derivation-prerequisites): Add 'input-set'
  variable, and use it in iterations.

* guix/sets.scm, tests/sets.scm: New files.sets
* Makefile.am (MODULES, SCM_TESTS): Add them.

* gnu/packages/qt.scm (qt): Add expat, pciutils, libxcomposite, libxcursor,
  libxfixes, libxinerama, libxml2, libxrandr, libxslt, libxtst, mtdev, nss,
  pcre, sqlite, eudev to 'inputs'.
  Add bison, flex, gperf, ninja, python-2, ruby, which to 'native-inputs'.

* gnu/packages/qt.scm (qt): Update to 5.4.0.
  [origin]: Add snippet.

* gnu/packages/ninja.scm: New file.
* gnu-system.am (GNU_SYSTEM_MODULES): Add it.

* gnu/packages/patches/nss-pkgconfig.patch: New file.
* gnu-system.scm (dist_patch_DATA): Add it.
* gnu/packages/gnuzilla.scm (nss): New variable.

* gnu/packages/polkit.scm (mozjs, nspr): Move to...
* gnu/packages/gnuzilla.scm (mozjs, nspr): ... here. New variables.

* gnu/packages/linux.scm (linux-libre): Update to version 3.18.2.

This makes 'guix environment PACKAGE' significantly faster when
substitutes are enabled.  Before that, it would lead to many invocations
of 'guix substitute-binary', one per 'derivation-prerequisites-to-build'
call.  Now, all these are replaced by a single invocation.

* guix/derivations.scm (derivation-output-paths, substitution-oracle):
  New procedures.
  (derivation-prerequisites-to-build): Replace #:use-substitutes? with
  #:substitutable?.  Remove the local 'derivation-output-paths' and
  'substitutable?'.
* guix/ui.scm (show-what-to-build): Add 'substitutable?'.  Pass it to
  'derivation-prerequisites-to-build'.
  [built-or-substitutable?]: Use it instead of 'has-substitutes?'.
* tests/derivations.scm ("derivation-prerequisites-to-build and
  substitutes"): Use #:substitutable? instead of #:use-substitutes?.

* guix/derivations.scm (derivation-output-names): New procedure.
  (derivation-prerequisites-to-build): Use it for #:outputs.
  (map-derivation): Likewise.
* tests/derivations.scm ("derivation-output-names"): New test.

* guix/import/cpan.scm, guix/scripts/import/cpan.scm, tests/cpan.scm:
  New files.
* Makefile.am (MODULE)[HAVE_GUILE_JSON]: Add them.
* guix/scripts/import.scm (importers): Add cpan.
* doc/guix.texi (Requirements): Mention `guix import cpan` as a user
  of guile-json.
  (Invoking guix import): Document new `guix import cpan` command.

* tests/pypi.scm (mock): Move this...
* guix/tests.scm: to here.

* guix/import/pypi.scm (hash-table->alist, flatten, assoc-ref*,
  url-fetch, json-fetch): Pull procedures from here into...
* guix/import/utils.scm: Here and...
* guix/import/json.scm: Here.  New file.
* Makefile.am (MODULE)[HAVE_GUILE_JSON]: Add it.
* guix/import/gnu.scm (file-sha256): Move from here to...
* guix/hash.scm: Here.
* tests/pypi.scm (pypi->guix-package): Update mock module reference.

* guix/import/gnu.scm (gnu->guix-package): Pass the key-download
  argument on to gnu-package->sexp.

* gnu/packages/pdf.scm (poppler): build poppler with openjpeg 1.5 and lcms.

* gnu/packages/image.scm (openjpeg): Update to 2.0.1.

* gnu/packages/image.scm (openjpeg-1): New variable.

* gnu/packages/image.scm (openjpeg)[home-page]: Update URL.

* guix/scripts/substitute-binary.scm (narinfo-signature->canonical-sexp):
  Change "~a" to "~s" in error message.
  (%signature-line-rx): Remove.
  (narinfo-sha256): Use 'string-contains' instead of 'regexp-exec', and
  'string-take' instead of 'match:substring'.

* guix/records.scm (%recutils-field-rx, %recutils-comment-rx,
  %recutils-plus-rx): Remove.
  (%recutils-field-charset): New variable.
  (recutils->alist): Adjust to use tests (string-ref line 0) instead of
  regexps.

* guix/base64.scm (define-alias): New macro.
  (fxbit-field, fxarithmetic-shift, fxarithmetic-shift-left, fxand,
  fxior, fxxor): New aliases.

* tests/lint.scm: Add missing copyright line for commit 907c98ac and
  others.