gnu: aria2: Update to 1.20.0.

* gnu/packages/bittorrent.scm (aria2): Update to 1.20.0.

gnu: glpk: Update to 4.58.

* gnu/packages/maths.scm (glpk): Update to 4.58.

gnu: ykclient: Update to 2.15.

* gnu/packages/yubico.scm (ykclient): Update to 2.15.

gnu: libyubikey: Update to 1.13.

* gnu/packages/yubico.scm (libyubikey): Update to 1.13.

gnu: yasm: Update to 1.3.0.

* gnu/packages/yasm.scm (yasm): Update to 1.3.0.

gnu: retroarch: Update to 1.3.1.

* gnu/packages/games.scm (retroarch): Update to 1.3.1.

gnu: Add emacs-popup.

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

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

gnu: Add gnome-backgrounds.

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

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

licenses: Add CC-BY-SA and CC-BY.

* guix/licenses.scm (cc-by-sa2.0, cc-by2.0): New variables.

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

emacs: Autoload hooks instead of putting them in 'guix-init'.

* emacs/guix-init.el: Move adding hooks to...
* emacs/guix-build-log.el: ... here.
* emacs/guix-devel.el: ... and here.

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

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

gnu: letsencrypt and python-acme: Update to 0.4.0.

These packages should be updated together.

* gnu/packages/tls.scm (letsencrypt): Update to 0.4.0.
(python-acme, python2-acme): Update to 0.4.0.

gnu: Add python-mako.

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

gnu: moe: Update to 1.8.

* gnu/packages/moe.scm (moe): Update to 1.8.

gnu: gnunet: Install NSS module.

* gnu/packages/gnunet.scm (gnunet)[arguments]: Pass '--with-nssdir'.

gnu: Add gnome.

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

gnu: Add mate-menus.

* gnu/packages/mate.scm (mate-menus): New variable.

gnu: Add libmateweather.

* gnu/packages/mate.scm (libmateweather): New variable.

gnu: Add mate-desktop.

* gnu/packages/mate.scm (mate-desktop): New variable.

gnu: Add mate-themes.

* gnu/packages/mate.scm (mate-themes): New variable.