gnu: linux-libre: Add 'supported-systems' field: Intel only for now.

* gnu/packages/linux.scm (linux-libre)[supported-systems]: New field.

gnu: linux-libre: Update to 4.2.5.

* gnu/packages/linux.scm (linux-libre): Update to 4.2.5.

linux-initrd: Use pata_acpi, pata_atiixp, and isci modules only on Intel.

* gnu/system/linux-initrd.scm (base-initrd)[linux-modules]: Include
  "pata_acpi", "pata_atiixp", and "isci" on Intel systems only.

system: grub: Adjust eye-candy to work on non-Intel systems.

* gnu/system/grub.scm (eye-candy): Accept additional 'system' argument.  Add
  local 'setup-gfxterm-body' variable.  Replace the 'load_video' grub function
  with 'setup_gfxterm', which includes everything in the 'if loadfont' form on
  Intel systems, but is empty on non-Intel.
  (grub-configuration-file): Pass 'system' to 'eye-candy.

system: grub: On MIPS, the linux image name is vmlinuz, not bzImage.

* gnu/system/grub.scm (grub-configuration-file): Add 'linux-image-name'
  internal procedure.  Use it from 'entry->gexp'.

gnu: Add Diffoscope.

* gnu/packages/package-management.scm (diffoscope): New variable.

gnu: Add python-chardet.

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

gnu: Add python-debian.

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

refresh: Add '--list-updaters' option.

* guix/scripts/refresh.scm (list-updaters-and-exit): New procedure.
  (%options, show-help): Add '--list-updaters' option.
* doc/guix.texi (Invoking guix refresh): Document it.

upstream: Add 'description' field to 'upstream-updater'.

Suggested by Ludovic Courtès <ludo@gnu.org>.

* guix/upstream.scm (<upstream-updater>): Use 'define-record-type*'.
  [description]: New field.
  (lookup-updater): Adjust accordingly.
* guix/gnu-maintenance.scm (%gnu-updater): Likewise.
* guix/import/cran.scm (%cran-updater): Likewise.
* guix/import/elpa.scm (%elpa-updater): Likewise.
* po/guix/POTFILES.in: Add guix/scripts/import/cran.scm and
  guix/gnu-maintenance.scm.

emacs: Use 'switch-to-generation*'.

This is a followup to commit 06d45f4566469364b4c1fe6d3c71ecf58f5d4838.

* emacs/guix-base.el (guix-switch-to-generation): Replace
  'switch-to-generation' with 'switch-to-generation*'.

emacs: Add "Packages" option for 'guix challenge' popup.

* emacs/guix-command.el (guix-command-rest-argument): Add "challenge".

emacs: Add shell completions for 'guix challenge'.

* emacs/guix-pcomplete.el (guix-pcomplete-complete-command-arg): Add
  "challenge" to complete package names for it.

gnu: gcj: Run libjava tests.

* gnu/packages/gcc.scm (gcj)[native-inputs]: Add dejagnu.
  [arguments]: Enable tests and set test target to
  "check-target-libjava".

gnu: guile-next: Update to 20151025.e5bccb6

* gnu/packages/guile.scm (guile-next): Update to 20151025.e5bccb6.

gnu: subread: Use SSE optimizations on x86_64 only.

* gnu/packages/bioinformatics.scm (subread)[arguments]: Override CC and
  CCFLAGS conditionally dependent on target system.

gnu: crossmap: Update to 0.2.1.

* gnu/packages/bioinformatics.scm (crossmap): Update to 0.2.1.

gnu: Add yapet.

* gnu/packages/password-utils.scm (yapet): New variable.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

gnu: Add xcompmgr.

* gnu/packages/xorg.scm (xcompmgr): New variable.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

profiles: Add generation manipulation procedures.

* guix/scripts/package.scm (delete-generations): Use
  'delete-generation*' instead of 'delete-generation'.
  (guix-package)[process-actions]: Use 'roll-back*' instead of
  'roll-back' and 'switch-to-generation*' instead of
  'switch-to-generation'.
  (link-to-empty-profile, switch-to-generation,
  switch-to-previous-generation, roll-back, delete-generation): Move
  to...
* guix/profiles.scm: ... here.  Adjust to not print messages and to
  return values that can be used by user interfaces.
* guix/ui.scm (display-generation-change, roll-back*,
  switch-to-generation*, delete-generation*): New procedures.