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.

gnu-maintenance: Really find the latest GNOME releases.

Reported by Efraim Flashner <efraim@flashner.co.il>
at <https://lists.gnu.org/archive/html/guix-devel/2015-12/msg00202.html>.

* guix/gnu-maintenance.scm (latest-ftp-release): Call KEEP-FILE? on
directories too.
(latest-gnome-release)[even-minor-version?]: Protect again MINOR being
false; change pattern to match VERSION with two or more numbers.  Remove
use of 'version-major+minor'.
[even-numbered-tarball?]: Rename to...
[even-numbered?]: ... this.  Use 'package-name->name+version'.  When
VERSION is #f, check NAME.

guix build: Add '--check'.

* guix/derivations.scm (build-derivations): Add optional 'mode'
parameter.
* guix/scripts/build.scm (%default-options): Add 'build-mode'.
(show-help, %options): Add '--check'.
(guix-build): Honor 'build-mode' key of OPTS.  Pass it to
'show-what-to-build' and 'build-derivations'.
* doc/guix.texi (Invoking guix build): Document it.
(Substitutes): Mention it.

derivations: Determine what's built in 'check' mode.

* guix/derivations.scm (substitution-oracle): Add #:mode parameter and
honor it.
(derivation-prerequisites-to-build): Likewise.
[derivation-built?]: Take it into account.
* guix/ui.scm (show-what-to-build): Add #:mode parameter.  Pass it to
'substitute-oracle' and 'derivations-prerequisites-to-build'.
* tests/derivations.scm ("derivation-prerequisites-to-build in 'check'
mode"): New test.

guix build: Add '--rounds'.

* guix/scripts/build.scm (show-build-options-help)
(%standard-build-options): Add --rounds.
(set-build-options-from-command-line): Honor it.
* doc/guix.texi (Invoking guix build): Document it.
* doc/contributing.texi (Submitting Patches): Mention it.

store: Allow clients to request multiple builds.

* guix/store.scm (set-build-options): Add #:rounds parameter and honor it.
* tests/store.scm ("build multiple times"): New test.

gnu-maintenance: Exclude development releases from GNOME update candidates.

Suggested by Efraim Flashner <efraim@flashner.co.il>.

* guix/gnu-maintenance.scm (latest-ftp-release): Add #:keep-file?
parameter and honor it.
(latest-gnome-release)[%not-dot]: New variable.
[even-minor-version?, even-numbered-tarball?]: New procedures.
Pass EVEN-NUMBERED-TARBALL? as #:keep-file? argument.

gnu-maintenance: ftp.gnome.org does not provide signatures.

* guix/gnu-maintenance.scm (latest-ftp-release): Add #:file->signature
parameter.  Honor it.
(latest-gnome-release): Pass #:file->signature.
* guix/upstream.scm (coalesce-sources): Keep 'signature-urls' as #f
unless both sources provide it.

gnu-maintenance: Add GNOME updater.

* guix/gnu-maintenance.scm (ftp-server/directory)[quirks]: Remove glib.
(false-if-ftp-error): New macro.
(latest-release*): Use it.
(non-emacs-gnu-package?): Rename to...
(pure-gnu-package?): ... this.  Add call to 'gnome-package?'.
(%gnu-updater): Adjust accordingly.
(gnome-package?, latest-gnome-release): New procedures.
(%gnome-updater): New variable.
* guix/scripts/refresh.scm (%updaters): Add %GNOME-UPDATER.
* doc/guix.texi (Invoking guix refresh): Mention it.

gnu-maintenance: Generalize 'latest-ftp-release'.

* guix/gnu-maintenance.scm (latest-release): Rename to...
(latest-ftp-release): ... this.  Add #:server and #:directory
parameters.
(latest-release): New procedure.

refresh: Bail out when asked for a nonexistent updater.

* guix/scripts/refresh.scm (lookup-updater): Call 'leave' when 'find'
returns #f.

gnu-maintenance: Do not look for releases in "w32" sub-directories.

* guix/gnu-maintenance.scm (latest-release): Filter out "w32"
directories.

gnu-maintenance: Add tests for 'release-file?'.

* tests/gnu-maintenance.scm: New file.
* Makefile.am (SCM_TESTS): Add it.
* guix/gnu-maintenance.scm (release-file?): Export.

gnu-maintenance: Properly handle TeXmacs.

* guix/gnu-maintenance.scm (ftp-server/directory): Add comment.
(release-file?): Use 'string-ci=?' instead of 'equal?' when comparing
project names.

gnu-maintenance: Adjust tarball regexp for IceCat tarballs.

* guix/gnu-maintenance.scm (%tarball-rx): Tweak to match IceCat tarball
patterns.

gnu-maintenance: Fix URLs returned by 'latest-release' for deep trees.

With this, (latest-release "gcc") returns an <upstream-source> with URL:

  ftp://ftp.gnu.org/gnu/gcc/gcc-5.3.0/gcc-5.3.0.tar.gz

Previous it would omit "gcc-5.3.0/" from the URL.

Fixes a regression introduced in 0a7c5a0.

* guix/gnu-maintenance.scm (latest-release)[file->url, file->source]:
Add 'directory' parameter.  Update users.

edit: Don't assume that an emacs daemon is running.

* guix/scripts/edit.scm (%editor): Use Emacs as a default value.

edit: Allow command line arguments in $VISUAL and $EDITOR.

* guix/scripts/edit.scm (guix-edit): Fix the assumption that %editor is
a one word command.

profiles: Silence GTK+ icon cache creation.

Suggested by Ricardo Wurmus <rekado@elephly.net>.

* guix/profiles.scm (gtk-icon-themes)[build]: Pass --quiet to
'gtk-update-icon-cache'.