guix package: Sort the list of generation numbers in '--list-generations'.

* guix/scripts/package.scm (generation-numbers): Sort the result.

guix package: Internationalize "Generation" string.

* guix/scripts/package.scm (guix-package): Internationalize generation
  listing.

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.

guix package: Rename generation-related procedures.

* guix/scripts/package.scm (profile-numbers): Rename to 'generation-numbers'.
  (previous-profile-number): Rename to 'previous-generation-number'.
  (profile-number): Rename to 'generation-number'.
  (roll-back): Rename 'previous-profile' to 'previous-generation'.

guix package: Allow separate install of several outputs of the same package.

* guix/scripts/package.scm (guix-package)[process-actions](same-package?):
  New procedure.  Use it instead of `alist-delete' when filtering out
  duplicate packages from the profile.

guix package: Fix handling of `-e'.

This fixes a bug whereby a command like

  guix package -e '(@@ (gnu packages base) gnu-make-boot0)'

would only succeed when the outputs of that package are available, and
otherwise fail with "/nix/store/... is not valid".

* guix/scripts/package.scm (guix-package)[process-action](package->tuple):
  Leave P as is in the result.  Move `package->tuple' call from INSTALL*
  to INSTALL.

guix package: Reuse FTP connections for subsequent `latest-release' calls.

* guix/gnu-maintenance.scm (latest-release): Add `ftp-close' and
  `ftp-open' keyword parameters.
* guix/scripts/package.scm (ftp-open*): New variable.
  (check-package-freshness): Call `latest-release' with `ftp-open*' and
  a no-op procedure.

Merge branch 'master' into core-updates

Conflicts:
	gnu/packages/make-bootstrap.scm

package: Fix i18n of the number of packages message.

* guix/scripts/package.scm (guix-package)[process-actions]: Use `N_' for
  i18n of the number of packages message.

package: Display the number of installed packages upon completion.

* guix/scripts/package.scm (guix-package)[process-actions]: Display the
  number of packages in the profile upon completion.

build, package: Add `--fallback' option.

* guix/scripts/build.scm (%options, show-help): Add `--fallback'.
  (guix-build): Call `set-build-options' with #:fallback?.
* guix/scripts/package.scm (%options, show-help): Add `--fallback'.
  (guix-package): Call `set-build-options' with #:fallback?.
* doc/guix.texi (Invoking guix package, Invoking guix build): Document
  `--fallback'.

package: Fix default profile ownership check when it's just been created.

* guix/scripts/package.scm (guix-package)[ensure-default-profile]: Check
  whether S is true before checking its owner.  Fixes the case where we
  built %PROFILE-DIRECTORY just above.

Add `--max-silent-time' to `guix build' and `guix package'.

* guix/scripts/build.scm (%default-options): Add default
  `max-silent-time' value.
  (show-help, %options):  Add `--max-silent-time'.
  (guix-build): Pass `max-silent-time' to `set-build-options'.
* guix/scripts/package.scm (%default-options): Add default
  `max-silent-time' value.
  (show-help, %options):  Add `--max-silent-time'.
  (guix-package): Pass `max-silent-time' to `set-build-options'.
* guix/ui.scm (string->number*): New procedure.
* tests/derivations.scm ("build-expression->derivation and
  max-silent-time"): New test.
* doc/guix.texi (Invoking guix package, Invoking guix build): Document
  `--max-silent-time'.

package: Make sure the profile directory is owned by the user.

* guix/scripts/package.scm (guix-package)[ensure-default-profile]: Check
  the owner of %PROFILE-DIRECTORY.  Report an error when the owner is
  not the current user.  Add `rtfm' procedure.
* doc/guix.texi (Invoking guix package): Mention the ownership test.

package: Always clear the SIGINT handler.

* guix/scripts/package.scm (call-with-sigint-handler): Wrap THUNK in
  `dynamic-wind' so that the SIGINT handler is always cleared.

ftp-client: Let callers handle `ftp-open' exceptions.

* guix/ftp-client.scm (ftp-open): Let exceptions through.
* guix/scripts/package.scm (waiting): Wrap EXP in a `dynamic-wind', so
  the line is always cleared.

package: Store the output path of packages installed with `-e'.

* guix/scripts/package.scm (guix-package)[process-actions](package->tuple):
  Put the output path in the tuple, not the derivation path.
* tests/guix-package.sh: Add test.

package: Make sure the dependencies get built along with the manifest.

Before this, something like "guix package -i glibc" could fail because
glibc lists linux-libre-headers as a propagated input (which would be
added as a dependency in the manifest) but the linux-libre-headers
output could be unavailable, leading to an error like this:

  path `/nix/store/4v2bk8sx5cm166gks3fi3q7d9zchibnk-linux-libre-headers-3.3.8' is not valid

This patch adds such dependencies as inputs of the profile derivation.

* guix/scripts/package.scm (profile-derivation): Accept package objects
  in the `deps' field of an element of PACKAGES.  Convert them to their
  output path for BUILDER, and add them to the inputs of the
  `build-expression->derivation' call.
  (input->name+path): When INPUT doesn't contain a package object,
  return it as is.
  (guix-package)[process-actions](canonicalize-deps): Expect DEPS to
  contain package objects, and leave them as is.

package: Use ~/.guix-profile as the default for --search-paths.

* guix/scripts/package.scm (search-path-environment-variables): Prefer
  %USER-ENVIRONMENT-DIRECTORY when it points to PROFILE.
  (display-search-paths): Use 3 spaces for indentation.