doc: Improve Info categories.

* doc/guix.texi: Change main category to "System administration".  Fix
syntax of subnodes.  Add entries for 'guix pull' and 'guix gc'.  Add
"Emacs" category.

utils: Use '@' for separating package names and version numbers.

This provides the ability to use numbers in package names.

Fixes <http://bugs.gnu.org/19219>.

* guix/utils.scm (package-name->name+version): New procedure.
* gnu/packages.scm (%find-package): Add a FALLBACK? keyword argument.
Use the previous method when no package is found.
(specification->package+output, specification->package): Adapt
documentation to new syntax.
* doc/guix.texi (Invoking guix package, Invoking guix import): Likewise.
* guix/ui.scm (package-specification->name+version+output): Likewise.
* guix/scripts/import/hackage.scm (show-help): Likewise.
* tests/guix-build.sh: Adapt to new syntax.
* tests/guix-lint.sh: Likewise.
* tests/guix-package.sh: Likewise.
* tests/ui.scm ("package-specification->name+version+output"): Likewise.
* tests/utils.scm ("package-name->name+version"): Likewise.
* NEWS: Mention new syntax.

guix build: Move '--no-grafts' to the common build options.

* guix/scripts/build.scm (%options): Move --no-grafts to...
(%standard-build-options): ... here.
(show-help, show-build-options-help): Adjust accordingly.
* guix/scripts/archive.scm (%default-options): Add 'graft?'.
(guix-archive): Parametrize '%graft?'.
* guix/scripts/environment.scm (%default-options): Add 'graft?'.
(guix-environment): Parametrize '%graft?'.
* guix/scripts/package.scm (%default-options): Add 'graft?'.
(guix-package): Parametrize '%graft?'.
* guix/scripts/system.scm (%default-options): Add 'graft?'.
(guix-system): Parametrize 'graft?'.
* doc/guix.texi (Additional Build Options): Move --no-grafts to...
(Common Build Options): ... here.

grafts: Graft recursively.

Fixes <http://bugs.gnu.org/22139>.

* guix/grafts.scm (graft-derivation): Rename to...
(graft-derivation/shallow): ... this.
(graft-origin-file-name, item->deriver, non-self-references)
(cumulative-grafts, graft-derivation): New procedures
* tests/grafts.scm ("graft-derivation, grafted item is a direct
dependency"): Clarify title.  Use 'grafted' instead of 'graft' to refer
to the grafted derivation.
("graft-derivation, grafted item is an indirect dependency")
("graft-derivation, no dependencies on grafted output"): New tests.
* guix/packages.scm (input-graft): Change to take a package instead of
an input.
(input-cross-graft): Likewise.
(fold-bag-dependencies): New procedure.
(bag-grafts): Rewrite in terms of 'fold-bag-dependencies'.
* tests/packages.scm ("package-derivation, indirect grafts"): Comment out.
* doc/guix.texi (Security Updates): Mention run-time dependencies and
recursive grafting.

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.

doc: Capitalize section title.

* doc/guix.texi (Running GuixSD in a VM): Capitalize section title.

Merge branch 'media-updates'

doc: Clarify the form of UUIDs we expect.

Fixes <http://bugs.gnu.org/22797>.
Reported by Alex Kost <alezost@gmail.com>.

* doc/guix.texi (File Systems): Clarify which UUIDs we're talking
about.

store: Clarify documentation of 'valid-path?'.

* guix/store.scm (valid-path?): Improve docstring.
* doc/guix.texi (The Store): Update accordingly.

doc: Improve recent changes in "Binary Installation".

This amends part of c8e2688.

* doc/guix.texi (Binary Installation): Improve wording of some parts.
Fix Upstart example.  Remove incorrect paragraph about locales.
Reinstate bit about reproducing the binary tarball.

doc: Clarify who can run 'guix pull'.

Suggested by Chris Marusich <cmmarusich@gmail.com>.

* doc/guix.texi (Invoking guix pull): Add paragraph explaining that any
user can run 'guix pull'.

doc: Add details for binary installation.

* doc/guix.texi (Binary Installation): Provide some more details for binary
  installation, in particular automatic starting of the daemon.

Signed-off-by: Andreas Enge <andreas@enge.fr>

doc: Fix minor typos and add missing words.

* doc/guix.texi (Shepherd Services): Add missing words.
  (Invoking guix system): Fix typo.
  (Service Types and Services): Fix typo.
* doc/contributing.texi (Submitting Patches): Fix typo.

Signed-off-by: Andreas Enge <andreas@enge.fr>

gnu-maintenance: Add X.org updater.

* guix/gnu-maintenance.scm (xorg-package?, latest-xorg-release): New
  private functions.
  (%xorg-updater): New public variable.

* guix/scripts/refresh.scm (%updaters): Add %xorg-updater.

* doc/guix.texi (Invoking guix refresh): Mention the new updater.

doc: Add example of VCS-snapshot version numbers.

* doc/guix.texi (Version Numbers): Add example for VCS version numbers.

emacs: Add 'M-x guix-installed-{user/system}-packages'.

* emacs/guix-ui-package.el (guix-installed-user-packages)
(guix-installed-system-packages): New commands.
* doc/emacs.texi (Emacs Commands): Document them.

doc: Add Texinfo HTML cross-reference file.

Fixes <http://bugs.gnu.org/22543>.

* doc/htmlxref.cnf: New file.
* doc.am (EXTRA_DIST): Add it.

Revert "doc: Drop documentation of deprecated procedures."

This reverts commit f5c6e77a7f42e133df8c97d3b4798a11e6d58d06.

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.

doc: Add footnote on Guile-JSON.

* doc/guix.texi ("invoking guix import"): Add a footnote to the CPAN importer
  on the need for Guile-JSON.