import: snix: Use the right 'package-name->name+version'.

Fixes a regression introduced in
1b846da8c372bee78851439fd9e72b2499115e5a.

* guix/import/snix.scm: Use 'package-name->name+version' from (guix
build utils).

import: Add github-updater.

* guix/import/github.scm: New file.
* guix/scripts/refresh.scm (%updaters): Add %GITHUB-UPDATER.
* doc/guix.texi (Invoking guix refresh): Mention it.
* Makefile.am (MODULES): Add gnu/import/github.scm.

import: gem: Add updater.

* guix/import/gem.scm (guix-package->gem-name,
  gem-package?, latest-release): New procedures.
  (%gem-updater): New variable.
  (rubygems-fetch): Wrap body in
  'call-with-output-file' and 'with-error-to-port'.
* guix/scripts/refresh.scm (%updaters): Add %GEM-UPDATER.
* doc/guix.texi (Invoking guix refresh): Mention RubyGems.

packages: Use '@' in package record printers.

* guix/packages.scm <package>: Use '@' in record printer.
* guix/import/cabal.scm <cabal-package>: Likewise
* guix/import/elpa.scm <elpa-package>: Likewise.
* tests/packages.scm: Adapt to it.

Merge branch 'master' into core-updates

import: gem: Beautify only the description, not the synopsis.

* guix/import/gem.scm (make-gem-sexp): Add synopsis argument.
(gem->guix-package): Pass unbeautified synopsis to make-gem-sexp.
* tests/gem.scm: Adapt it.

import: Add Bioconductor importer and updater.

* guix/import/cran.scm (%bioconductor-updater,
latest-bioconductor-release, bioconductor-package?): New procedures.
(cran->guix-package): Support repositories other than CRAN.
(%bioconductor-url, %bioconductor-svn-url): New variables.
(description->package): Update signature to distinguish between packages
from different repositories.
(latest-release): Rename procedure ...
(latest-cran-release): ... to this.
(cran-package?): Do not assume all R packages are available on CRAN.
* tests/cran.scm: Update tests.
* guix/scripts/import/cran.scm: Add "--archive" option and default to
CRAN.
* guix/scripts/refresh.scm (%updaters): Add "%bioconductor-updater".
* doc/guix.texi: Document Bioconductor importer and updater.

Merge branch 'master' into core-updates

import: gem: Beautify description field.

* guix/import/gem.scm (gem->guix-package): Use 'beautify-description'.

import: cran: Move beautify-description to utils module.

* guix/import/cran.scm (beautify-description): Move from here...
* guix/import/utils.scm: ... to here.

Merge branch 'master' into core-updates

import: Rename "cran-fetch" to "fetch-description".

* guix/import/cran.scm (cran-fetch): Rename procedure ...
(fetch-description): ... to this.

import: Add package->upstream-name procedure.

* guix/import/cran.scm (package->upstream-name): New procedure.

Merge branch 'master' into core-updates

import: Drop empty list items.

* guix/import/cran.scm (listify): Remove empty strings from result list.

Merge branch 'master' into core-updates

import: cran: Parse DESCRIPTION instead of HTML.

* guix/import/cran.scm (description->alist, listify,
  beautify-description, description->package): New procedures.
(table-datum, downloads->url, nodes->text, cran-sxml->sexp): Remove
proceduces.
(latest-release): Use parsed DESCRIPTION instead of SXML.
* tests/cran.scm: Rewrite to match importer.

import: cran: Match more license strings.

* guix/import/cran.scm (string->license): Match more license strings to
  license symbols.

import: pypi: Updater silently ignores packages without source.

Reported by Andreas Enge <andreas@enge.fr>
at <https://lists.gnu.org/archive/html/guix-devel/2015-11/msg00764.html>.

* guix/import/pypi.scm (&missing-source-error): New error type.
(latest-source-release): Raise it instead of using 'error'.
(pypi->guix-package): Guard against it and use 'leave' to report the
error.
(latest-release): Guard against it and return #f when caught.

import: hackage: Handle CRLF end of line style.

* guix/import/hackage.scm (hackage-fetch, hackage->guix-package): Use
  'canonical-newline-port'.