Merge branch 'master' into core-updates

guix package: Do not list the zeroth generation.

* guix/scripts/package.scm (guix-package)[process-query]: Change
  'list-generation' to not list the zeroth generation.
* tests/guix-package.sh: Test it.
* doc/guix.texi (Invoking guix package): Document it, and use the
  right term when talking about generations.

Merge branch 'master' into core-updates

doc: Document '--list-generations' among the query options.

* doc/guix.texi (Invoking guix package): Move '--list-generations' below
  "In addition to these actions".

guix package: Show most recently installed packages last.

Suggested by Andreas Enge <andreas@enge.fr>.

* guix/scripts/package.scm (guix-package)[list-generations,
  list-installed]: Reverse the result of 'manifest-packages'.
* doc/guix.texi (Invoking guix package): Document the order of packages
  for '--list-generations' and '--list-installed'.

guix package: Add '--list-generations'.

* guix/scripts/package.scm: Import (srfi srfi-19).
  (generation-time, matching-generations): New functions.
  (show-help): Add '--list-generations'.
  (%options): Likewise.
  (guix-package)[process-query]: Add support for '--list-generations'.
* guix/ui.scm: Import (srfi srfi-19) and (ice-9 regex).
  (string->generations, string->duration): New functions.
* tests/guix-package.sh: Test '--list-generations'.
* tests/ui.scm: Import (srfi srfi-19).
  Test 'string->generations' and 'string->duration'.
* doc/guix.texi (Invoking guix-package): Document '--list-generations'.

derivations: 'derivation' and related procedures return a single value.

* guix/derivations.scm (derivation->output-path,
  derivation->output-paths): New procedures.
  (derivation-path->output-path): Use 'derivation->output-path'.
  (derivation-path->output-paths): Use 'derivation->output-paths'.
  (derivation): Accept 'derivation?' objects as inputs.  Return a single
  value.
  (build-derivations): New procedure.
  (compiled-modules): Use 'derivation->output-paths'.
  (build-expression->derivation)[source-path]: Add case for when the
  input matches 'derivation?'.
  [prologue]: Accept 'derivation?' objects in INPUTS.
  [mod-dir, go-dir]: Use 'derivation->output-path'.
* guix/download.scm (url-fetch): Adjust to the single-value return.
* guix/packages.scm (package-output): Use 'derivation->output-path'.
* guix/scripts/build.scm (guix-build): When the argument is
  'derivation-path?', pass it through 'read-derivation'.
  Use 'derivation-file-name' to print out the .drv file names, and to
  register them.  Use 'derivation->output-path' instead of
  'derivation-path->output-path'.
* guix/scripts/package.scm (roll-back): Adjust to the single-value
  return.
  (guix-package): Use 'derivation->output-path'.
* guix/ui.scm (show-what-to-build): Adjust to deal with 'derivation?'
  objects instead of .drv file names.
* gnu/system/grub.scm (grub-configuration-file): Use
  'derivation->output-path' instead of 'derivation-path->output-path'.
* gnu/system/vm.scm (qemu-image, system-qemu-image): Likewise.
* tests/builders.scm, tests/derivations.scm, tests/packages.scm,
  tests/store.scm, tests/union.scm: Adjust to the new calling
  convention.
* doc/guix.texi (Defining Packages, The Store, Derivations): Adjust
  accordingly.

store: The 'references' parameter of 'add-text-to-store' is now optional.

* guix/store.scm (add-text-to-store): Make 'references' optional.
* tests/store.scm ("dead-paths", "references"): Use 'add-text-to-store'
  with no optional argument.
* doc/guix.texi (The Store): Adjust accordingly.

Merge branch 'master' into core-updates

doc: Stylistic changes to "Packaging Guidelines"

doc: Remove an extra space after @ref.

doc: Add duplicate copyright notice again.

* doc/guix.texi: Add second copyright notice again inside @ifinfo, needed
  since the first one does not appear in the info output.
  Partially undoes commit da7cabd.

doc: Fix the image size in PDF/PS/DVI output.

* doc/guix.texi (Bootstrapping): Specify an image width for the TeX
  output.  Before that, the image would be much wider than the US Letter
  page width.

doc: Add package guidelines for names and numbers.

* doc/guix.texi: Three new subsections.

doc: Shuffle some text around.

* doc/guix.texi: Drop duplicate copyright notice, start section
    "Packaging Guidelines" with existant text.

doc: Create own Makefile.am in subdirectory.

* doc/Makefile.am: New file.
* Makefile.am: Reference subdirectory doc.

derivations: Rename #:dependency-graphs to #:references-graphs.

* guix/derivations.scm (derivation, build-expression->derivation):
  Rename #:dependency-graphs to #:references-graphs, for consistency in
  the terminology.
* tests/derivations.scm: Adjust accordingly.

derivations: Add #:dependency-graphs to `build-expression->derivation'.

* guix/derivations.scm (build-expression->derivation): Add
  #:dependency-graphs keyword argument.  Pass it to `derivation'.
* tests/derivations.scm ("build-expression->derivation with
  #:dependency-graphs"): New test.
* doc/guix.texi (Derivations): Update `build-expression->derivation'
  description.

derivations: Add #:dependency-graphs `derivation' parameter.

* guix/derivations.scm (derivation): Add `dependency-graphs' keyword
  parameter; honor it.
* tests/derivations.scm (bootstrap-binary): New procedure.
  (%bash): Use it.
  (%mkdir): New variable.
  (directory-contents): Add `slurp' optional parameter.
  ("derivation with #:dependency-graphs"): New test.
* doc/guix.texi (Derivations): Update accordingly.

derivations: Move 3 positional parameters into keyword parameters.

* guix/derivations.scm (derivation): Turn `system', `env-vars', and
  `inputs' into keyword parameters.
  (build-expression->derivation): Adjust accordingly.
* gnu/packages/bootstrap.scm (%bootstrap-guile): Likewise.
* tests/derivations.scm, tests/store.scm: Likewise.
* doc/guix.texi (Derivations): Likewise.