guix download: Honor the number of columns of the terminal.

* guix/scripts/download.scm (guix-download): Parameterize
'current-terminal-columns'.

ui: Use 'terminal-columns'.

* guix/ui.scm (%text-width): Default to (terminal-columns).

ui: 'package->recutils' accurately honors the number of columns.

* guix/ui.scm (package->recutils)[width*]: New variable.  Use it instead
of WIDTH.

syscalls: Add TIOCGWINSZ bindings.

* guix/build/syscalls.scm (TIOCGWINSZ): New macro.
(<window-size>): New record type.
(winsize): New C struct.
(winsize-struct): New variable.
(terminal-window-size, terminal-columns): New procedures.

download: Add 'current-terminal-columns' parameter.

* guix/build/download.scm (current-terminal-columns): New variable.
(progress-proc): Use it instead of the hard-coded "80".

download: Send an ANSI erase-in-line sequence in addition to CR.

Partly fixes <http://bugs.gnu.org/22536>.
Reported by Danny Milosavljevic <dannym@scratchpost.org>.

* guix/build/download.scm (progress-proc): Send an ANSI erase-in-line
sequence.

gnu-maintenance: Move FTP directory info to 'properties' fields.

* guix/gnu-maintenance.scm (ftp-server/directory): Rewrite to honor
PACKAGE's properties.  Remove list of quirks.
(releases): Add #:server and #:directory parameters.  Remove call
to 'ftp-server/directory'.
(latest-release): Likewise.
(latest-release*): Add call to 'ftp-server/directory'.  Honor
'upstream-name' property of PACKAGE.
* gnu/packages/fonts.scm (font-gnu-freefont-ttf): Add 'properties'
field.
* gnu/packages/gnupg.scm (libgpg-error, libgcrypt, libassuan):
(libksba, gnupg): Likewise.
* gnu/packages/gnuzilla.scm (icecat): Likewise.
* gnu/packages/package-management.scm (guix-0.10.0): Likewise.
* gnu/packages/pretty-print.scm (source-highlight): Likewise.
* gnu/packages/scheme.scm (mit-scheme): Likewise.
* gnu/packages/telephony.scm (ucommon): Likewise.
* gnu/packages/tls.scm (gnutls): Likewise.

gnu-maintenance: Recognize source tarball with "-src" in their name.

* guix/gnu-maintenance.scm (tarball->version): Add special case for
tarball names containing "-src".

upstream: Pass a package object to updaters.

* guix/upstream.scm (package-update-path): Pass PACKAGE to
'latest-release'.
* guix/gnu-maintenance.scm (latest-release*)
(latest-gnome-release, latest-xorg-release): Adjust accordingly.
* guix/import/cran.scm (latest-cran-release):
(latest-bioconductor-release): Likewise.
* guix/import/elpa.scm (latest-release): Likewise.
* guix/import/gem.scm (latest-release): Likewise.
* guix/import/github.scm (latest-release): Likewise.
* guix/import/hackage.scm (latest-release): Likewise.
* guix/import/pypi.scm (latest-release): Likewise.

Revert "gnu: util-linux: Add "static" output."

This reverts commit df887432be25e1534b9ecdccf39c98857b1d0786.

gnu: r-htmltools: Update to 0.3.5.

* gnu/packages/web.scm (r-htmltools): Update to 0.3.5.
[propagated-inputs]: Add r-rcpp.

gnu: Add r-nnet.

* gnu/packages/machine-learning.scm (r-nnet): New variable.

gnu: Add r-igraph.

* gnu/packages/statistics.scm (r-igraph): New variable.

gnu: Add r-nmf.

* gnu/packages/statistics.scm (r-nmf): New variable.

gnu: Add r-rngtools.

* gnu/packages/statistics.scm (r-rngtools): New variable.

gnu: Add r-registry.

* gnu/packages/statistics.scm (r-registry): New variable.

gnu: Add r-pkgmaker.

* gnu/packages/statistics.scm (r-pkgmaker): New variable.

gnu: Add r-irlba.

* gnu/packages/statistics.scm (r-irlba): New variable.

gnu: Add r-latticeextra.

* gnu/packages/statistics.scm (r-latticeextra): New variable.

gnu: Add r-xtable.

* gnu/packages/statistics.scm (r-xtable): New variable.