nar: Implement restoration from Nar.

* guix/nar.scm (&nar-error, &nar-read-error): New condition types.
  (dump): New procedure.
  (write-contents)[dump]: Remove.  Use the one above instead.
  (read-contents, write-file, restore-file): New procedures.
  (%archive-version-1): New variable.

Add preliminary binary substituter.

* guix/scripts/substitute-binary.scm: New file.
* Makefile.am (MODULES): Add it.
* nix/scripts/substitute-binary.in: New file.
* config-daemon.ac: Produce nix/scripts/substitute-binary.
* daemon.am (nodist_pkglibexec_SCRIPTS): Add
  nix/scripts/substitute-binary.
* guix/store.scm (substitutable-path-info): Use the
  `query-substitutable-path-infos' RPC.
* nix/nix-daemon/guix-daemon.cc (main): Honor `NIX_SUBSTITUTERS'.
* pre-inst-env.in: Set `NIX_SUBSTITUTERS'.
* test-env.in: Leave `NIX_SUBSTITUTERS' unchanged.  Set
  `GUIX_BINARY_SUBSTITUTE_URL, and create
  $NIX_STATE_DIR/substituter-data.
  Run `guix-daemon' within `./pre-inst-env'.
* tests/store.scm ("substitute query"): New test.

store: Add `store-path-hash-part'.

* guix/store.scm (store-path-hash-part): New procedure.
* tests/store.scm ("store-path-hash-part", "store-path-hash-part #f"):
  New tests.

packages: Remove the default value for `license'.

* guix/packages.scm (<package>): Remove the default value for `license'.
* gnu/packages/bootstrap.scm (package-from-tarball,
  %bootstrap-glibc, %bootstrap-gcc): Initialize `license'.
* tests/packages.scm (dummy-package): Likewise.

guix package: Add `--install-from-expression'.

* guix/scripts/package.scm (read/eval-package-expression): New
  procedure.
  (show-help): Add `-e'.
  (%options): Likewise.
  (guix-package)[process-actions]: Handle ('install . p) pairs, where P
  is a package.
* tests/guix-package.sh: Add `boot_make_drv'.  Use `-i $boot_make_drv'
  once, and then use `-e $boot_make'.
* doc/guix.texi (Invoking guix package): Document `-e'.

guix gc: Add `--references' and `--referrers'.

* guix/scripts/gc.scm (show-help): Update.
  (%options): Add `--references' and `--referrers'.
  (guix-gc)[symlink-target, store-directory]: New procedures.
  Handle the `list-references' and `list-referrers' actions.
* tests/guix-gc.sh: Add tests for `--references'.
* doc/guix.texi (Invoking guix gc): Document `--references' and
  `--referrers'.

store: Add queries for references & co.

* guix/store.scm (operation-id)[query-valid-derivers]: New value.
  (references, referrers, valid-derivers, query-derivation-outputs): New
  procedures.
* tests/store.scm ("references", "derivers"): New tests.

Replace individual scripts with master 'guix' script.

* scripts/guix.in: New script.

* Makefile.am (bin_SCRIPTS): Add 'scripts/guix'.  Remove 'guix-build',
  'guix-download', 'guix-import', 'guix-package', and 'guix-gc'.

  (MODULES): Add 'guix/scripts/build.scm', 'guix/scripts/download.scm',
  'guix/scripts/import.scm', 'guix/scripts/package.scm', and
  'guix/scripts/gc.scm'.

* configure.ac (AC_CONFIG_FILES): Add 'scripts/guix'.  Remove 'guix-build',
  'guix-download', 'guix-import', 'guix-package', and 'guix-gc'.

* guix-build.in, guix-download.in, guix-gc.in, guix-import.in,
  guix-package.in: Remove shell script boilerplate.  Move to guix-COMMAND.in
  to guix/scripts/COMMAND.scm.  Rename module from (guix-COMMAND) to
  (guix scripts COMMAND).  Change "guix-COMMAND" to "guix COMMAND" in
  usage help string.

* pre-inst-env.in: Add "@abs_top_builddir@/scripts" to the front of $PATH.
  Export $GUIX_UNINSTALLED.

* tests/guix-build.sh, tests/guix-daemon.sh, tests/guix-download.sh,
  tests/guix-gc.sh, tests/guix-package.sh: Use "guix COMMAND" instead of
  "guix-COMMAND".

* doc/guix.texi: Replace all occurrences of "guix-COMMAND" with
  "guix COMMAND".

* po/POTFILES.in: Update.

packages: Add `package-output'.

* guix/packages.scm (package-output): New procedure.
* tests/packages.scm ("package-output"): New test.

union: Delete duplicates when passed the same input several times.

* guix/build/union.scm (union-build): Prepend "." to the result of
  `union-tree', to match the expectations of `delete-duplicate-leaves'.
  Don't do mkdir when SUBDIR is ".".
* tests/union.scm ("union-build"): Keep duplicates in %BOOTSTRAP-INPUTS.

guix-package: Test installation of packages by name.

* tests/guix-package.sh: Remove `boot_guile'.  Replace occurrences of
  $boot_guile by the `guile-bootstrap' package name.

store: Add substitute-related procedures.

* guix/store.scm (has-substitutes?, substitutable-paths,
  read-substitutable-path-list, substitutable-path-info): New
  procedures.
  (<substitutable>): New record type.
  (read-arg): Add `substitutable-path-info'.  Change `hash' pattern
  variable to `base16' literal.
* tests/store.scm ("no substitutes"): New test.

tests: Fix thinko in `derivation' test.

* tests/derivations.scm ("derivation with local file as input"): Return
  a Boolean instead of a bytevector.  Don't attempt to compare the
  content of the result with that of the input.

Augment `.dir-locals.el'.

* .dir-locals.el: Add more Scheme settings.
* guix-build.in, tests/base32.scm, tests/build-utils.scm,
  tests/builders.scm, tests/derivations.scm, tests/packages.scm,
  tests/snix.scm, tests/store.scm, tests/union.scm, tests/utils.scm:
  Remove redundant Emacs local variable settings.

guix-package: Report `--search' matches in recutils format.

* guix/ui.scm (fill-paragraph, string->recutils, package->recutils): New
  procedures.
* guix-package.in (guix-package)[process-query]: Use `package->recutils'
  to display package meta-data.
* tests/guix-package.sh: Adjust test.
* tests/ui.scm: New file.
* Makefile.am (TESTS): Add it.
* doc/guix.texi (Invoking guix-package): Adjust `--search'
  documentation, and give an example.

guix-package: Gracefully report non-existing outputs.

* guix-package.in (guix-package)[find-package](ensure-output): New
  procedure. Use it to validate SUB-DRV.

store: Remove the `fixed?' parameter from `add-to-store'.

* guix/store.scm (add-to-store): Remove the `fixed?' parameter from the
  public interface.
* gnu/packages/bootstrap.scm, guix-download.in, guix/derivations.scm,
  guix/packages.scm, tests/derivations.scm: Update all callers
  accordingly.

guix-package: Add '--search'.

* guix-package.in (find-packages-by-description): New procedure.
  (show-help, %options): Add '--search'.
  (guix-package)[process-query]: Add support for '--search'.
* doc/guix.texi (Invoking guix-package): Document it.
* tests/guix-package.sh: Add tests.

guix-package: Always use the next number for new generations.

Suggested by Andreas Enge <andreas@enge.fr> at
<http://lists.gnu.org/archive/html/bug-guix/2013-01/msg00325.html>.

* guix-package.in (latest-profile-number): Remove.
  (switch-symlinks): New procedure.
  (roll-back)[switch-link]: Use it.
  (guix-package)[process-actions]: Always choose NUMBER + 1 for the new
  profile.  Use `switch-symlinks' instead of `symlink'.  Remove code to
  delete PROFILE when it exists since `switch-symlinks' has the same
  effect.
* tests/guix-package.sh: Adjust existing `--roll-back' tests.
* doc/guix.texi (Invoking guix-package): Document this `--roll-back'
  behavior.

guix-package: When rolling back to nothingness, point to the empty profile.

Suggested by Andreas Enge <andreas@enge.fr> at
<http://lists.gnu.org/archive/html/bug-guix/2013-01/msg00316.html>.

* guix-package.in (roll-back): Check whether PROFILE is valid using
  `file-exists?'.  When NUMBER is zero, just emit a notice.  When
  PREVIOUS-NUMBER is zero and PREVIOUS-PROFILE does not exist, build the
  empty profile, and link to it.
* tests/guix-package.sh: Add tests.
* doc/guix.texi (Invoking guix-package): Document the new behavior.