download: Remove a SourceForge mirror that never returns 404.

* guix/download.scm (%mirrors)[sourceforge]: Remove
nbtelecom.dl.sourceforge.net, which never returns 404 responses.  This causes
download failures due to hash mismatch, effectively preventing secondary
source URLs from being queried.

packages: Use Guile 2.0 for grafting.

Works around <https://bugs.gnu.org/28211>.
Reported by Marius Bakke <mbakke@fastmail.com>.

* guix/packages.scm (guile-2.0): New procedure.
(package-derivation, package-cross-derivation): Use it when computing
the #:guile argument to 'graft-derivation'.

Merge branch 'master' into core-updates

gnu: gnurl: Update to 7.55.1.

* gnu/packages/gnunet.scm (gnurl): Update to 7.55.1.

Signed-off-by: Tobias Geerinckx-Rice <me@tobias.gr>

gnu: vifm: Update to 0.9.

* gnu/packages/vim.scm (vifm): Update to 0.9.
[source]: Add alternate uri.
[arguments]: Remove build timestamp. Add phase to install vim plugins
into vim plugin directory. Patch more shebangs.

gnu: pspp: Update to 1.0.0.

* gnu/packages/statistics.scm (pspp): Update to 1.0.0.

gnu: perl-test-trap: Update to 0.3.2.

* gnu/packages/perl.scm (perl-test-trap): Update to 0.3.2.
[source, version]: Remove 'v' prefix from version field.

gnu: perl-test-trap: Add missing dependency on Test::Simple.

* gnu/packages/perl.scm (perl-test-trap)[native-inputs]: Add PERL-TEST-SIMPLE.

gnu: bundler: Update to 1.15.4.

* gnu/packages/ruby.scm (bundler): Update to 1.15.4.

gnu: limnoria: Update to 2017.08.18.

* gnu/packages/irc.scm (limnoria): Update to 2017.08.18.

guix download: Support retrieving local file without the URI scheme.

* guix/scripts/download.scm (guix-download): Treat the URL argument as a local
file path when it fails on 'string->uri'.  Call 'fetch' with the processed
'uri' instead of the original URL argument.
* tests/guix-download.sh: Adjust accordingly.

gnu: graphicsmagick: Fix CVE-2017-{12935,12936,12937}.

* gnu/packages/patches/graphicsmagick-CVE-2017-12935.patch,
gnu/packages/patches/graphicsmagick-CVE-2017-12936.patch,
gnu/packages/patches/graphicsmagick-CVE-2017-12937.patch: New files.
* gnu/local.mk (dist_patch_DATA): Add them.
* gnu/packages/imagemagick.scm (graphicsmagick)[source]: Use them.

gnu: r-minimal: Work around failure to embed reference to "which".

* gnu/packages/statistics.scm (r-minimal)[arguments]: Add phase "patch-which".
[native-inputs]: Move "which" from here...
[propagated-inputs]: ...to here.

gnu: powertabeditor: Update to 2.0.0-alpha10.

* gnu/packages/music.scm (powertabeditor): Update to 2.0.0-alpha10.
[arguments]: Remove "set-target-directories" phase; disable additional tests.

gnu: Add r-annotationfilter.

* gnu/packages/bioinformatics.scm (r-annotationfilter): New variable.

gnu: Add gnome-default-applications.

* gnu/packages/gnome.scm (gnome-default-applications): New public variable.
(gnome): Propagate gnome-default-applications so that nautilus is associated
with folders, not baobab.

gnu: gnome: Propagate font-dejavu.

* gnu/packages/gnome.scm (gnome): Add font-dejavu to propagated inputs, to
  provide a better default for "Monospace".  Otherwise the terminal looks
  horrible and defaults to Nimbus Mono, a Courier-like face.

gnu: gobby: Re-add Gobby 0.4.

* gnu/packages/gobby.scm (gobby-0.4): New variable.

gnu: gnome: Propagate more packages.

* gnu/packages/gnome.scm (gnome): Add additional dependencies, inspired by
  Debian's "gnome-core" package.

gnu: grub-efi-bootloader: Specialize grub-install invocation.

* gnu/bootloader/grub.scm (install-grub-efi): Fix grub-install invocation for
  EFI systems.
* gnu/system/examples/bare-bones.tmpl: Use the newer
"bootloader-configuration" syntax.
* gnu/system/examples/desktop.tmpl: Use bootloader-configuration sytax.  Also,
use the same label for the LUKS-mapped device and the root partition.  Remove
unneeded "title" field for the file-system based on LUKS; as noted in the
manual, the "title" field is ignored for mapped devices.
* gnu/system/examples/lightweight-desktop.tmpl: Use bootloader-configuration,
and use grub-efi-bootloader.