gnu: python-numpy-bootstrap: Reduce matrix size in failing test.

* gnu/packages/python.scm (python-numpy-bootstrap): Add phase
  'fix-failing-tests.

gnu: Add xdotool.

* gnu/packages/xdisorg.scm (xdotool): New variable.

install: Use a low-memory nscd caching policy.

* gnu/system/install.scm (%nscd-minimal-caches): New variable.
  (installation-services): Use as 'nscd-service' argument.

services: Make 'nscd-service' configurable; cache hosts/services by default.

Before that, as it was given an empty configuration file, nscd would
actually have all its caches disabled.

* gnu/services/base.scm (<nscd-configuration>, <nscd-cache>): New record
  types.
  (%nscd-default-caches, %nscd-default-configuration): New variables.
  (nscd.conf-file): New procedure.
  (nscd-service): Add 'config' parameter.  Use 'nscd.conf-file', and
  pass its result as the '-f' parameter of nscd.
* doc/guix.texi (Base Services): Update 'nscd-service' documentation
  accordingly.  Document 'nscd-configuration', 'nscd-cache',
  '%nscd-default-configuration', and '%nscd-default-caches'.

activation: Copy the account skeletons when creating the 'root' account.

* gnu/build/activation.scm (%skeleton-directory): New variable.
  (dot-or-dot-dot?, copy-account-skeletons): New procedure.
  (add-user): Use 'copy-account-skeletons'.
  (activate-etc): Use 'dot-or-dot-dot?'.

system: grub: Make sure the font and background image are always found.

* gnu/system/grub.scm (eye-candy): Add 'search --file --set'.

system: Adjust 'grub.cfg' to work on systems with a separate /boot.

Fixes <http://bugs.gnu.org/19220>.
Reported by Nikita Karetnikov <nikita@karetnikov.org>.

* gnu/system/grub.scm (grub-configuration-file)[entry->gexp]: Add
  'search --file --set'.
  (grub-configuration-file)[builder]: Remove 'search.file'.

vm: Use QEMU's standard VGA emulation by default.

* gnu/system/vm.scm (common-qemu-options): Add "-vga std".

services: xorg: Run the window manager from a login shell.

This is a followup to 1d18d87, which fixes <http://bugs.gnu.org/19119>.

* gnu/services/xorg.scm (xinitrc)[builder]: Add 'exec-from-login-shell'
  procedure.  Use it instead of 'execl' when launching XSESSION, WMAKER,
  or RATPOISON.

system: Add sudo to '%base-packages'.

* gnu/system.scm (%base-packages): Add SUDO.

gnu: python-numpy-bootstrap: Make tests verbose.

* gnu/packages/python.scm (python-numpy-bootstrap): Make tests verbose to
  allow test failure debugging on hydra.

gnu: xfconf: Disable parallel tests.

* gnu/packages/xfce.scm (xfconf): Add 'arguments' field.

gnu: Add samtools

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

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

system: /etc/profile defines 'MANPATH', which includes the global profile.

* gnu/system.scm (etc-directory)[profile]: Set 'MANPATH'.

gnu: Add nginx.

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

gnu: pcre: Update to 8.36 and enable JIT support.

* gnu/packages/pcre.scm (pcre): Update to 8.36.  Enable JIT support.

gnu: Add xfdesktop.

* gnu/packages/xfce.scm (xfdesktop): New variable.

gnu: Add xfwm4.

* gnu/packages/xfce.scm (xfwm4): New variable.

gnu: Add thunar-volman.

* gnu/packages/xfce.scm (thunar-volman): New variable.

gnu: Add thunar.

* gnu/packages/xfce.scm (thunar): New variable.