daemon: Add `--listen'.

* nix/nix-daemon/guix-daemon.cc (GUIX_OPT_LISTEN): New macro.
  (options): Add `--listen'.
  (parse_opt): Handle it.
* doc/guix.texi (Invoking guix-daemon): Mention it.

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.

Build newest versions unless specified, and implement upgrades.

* gnu/packages.scm (find-newest-available-packages):
  New exported procedure.

* guix-build.in (newest-available-packages, find-best-packages-by-name):
  New procedures.
  (find-package): Use find-best-packages-by-name, to guarantee that
  if a version number is not specified, only the newest versions will
  be considered.

* guix-package.in (%options): Add --upgrade/-u option.
  (newest-available-packages, find-best-packages-by-name, upgradeable?):
  New procedures.
  (find-package): Use find-best-packages-by-name, to guarantee that
  if a version number is not specified, only the newest versions will
  be considered.
  (process-actions): Implement upgrade option.

* doc/guix.texi (Invoking guix-package): In the description of --install,
  mention that if no version number is specified, the newest available
  version will be selected.

doc: Document installation of propagated inputs.

* doc/guix.texi (Invoking guix-package): Document installation behavior
  with propagated inputs.

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: 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.

doc: Clarify that `guix-build' really is for developers.

* doc/guix.texi (Invoking guix-build): Make it clear that `guix-build'
  doesn't access the user's profile, and add cross-ref to `guix-package'.
  Suggested by Nikita Karetnikov <nikita@karetnikov.org>.

doc: Improve wording and fix typos in "Features".

* doc/guix.texi (Features): Fix typos, and rephrase according to the
  suggestions of Alex Sassmannshausen <alex.sassmannshausen@gmail.com>.

guix-build: Allow version-qualified package names.

* guix-build.in (guix-build)[find-package]: New procedure.
  Use it instead of using `find-packages-by-name' directly.
  Suggested by Andreas Enge <andreas@enge.fr>.
* tests/guix-build.sh: Add tests.
* doc/guix.texi (Invoking guix-build): Add `coreutils-8.20' as an
  example.  Fix guile-1.8 example.

packages: Have `package-derivation' return a <derivation> as a second value.

* guix/packages.scm (cache): Change the `drv' argument to `thunk'.
  Memoize all the return values of THUNK.
  (cached-derivation): Remove.
  (cached): New macro.
  (package-derivation): Use `cached' instead of `(or (cached-derivation) …)'.
* doc/guix.texi (Defining Packages): Update accordingly.

doc: Run `useradd -g guix-builder -G guix-builder'.

* doc/guix.texi (Setting Up the Daemon): Add `-G guix-builder' when
  invoking `useradd'.
  Suggested by Aleix Conchillo Flaqué <aconchillo@gmail.com>.

doc: Add a "GNU Distribution" node.

* doc/guix.texi (Introduction): Add cross-reference to "GNU
  Distribution".
  (Features): Mention reproducibility.
  (Invoking guix-package): Add cross-reference to "GNU Distribution".
  (GNU Distribution): New node.

doc: Mark binary deployment as not implemented yet.

* doc/guix.texi (Features): Add a footnote saying that binary deployment
  is missing.

guix-package: Add `--roll-back'.

Based on a patch by Nikita Karetnikov <nikita@karetnikov.org>.

* guix-package.in (profile-regexp): New procedure.
  (latest-profile-number): Remove `%profile-rx', and use
  `profile-regexp' instead.
  (profile-number, roll-back): New procedure.
  (show-help): Add `--roll-back'.
  (%options): Likewise.
  (guix-package)[process-actions]: First check whether `roll-back?' is
  among OPTS, and call `roll-back' if it is, followed by a recursive
  call to `process-actions'.  Emit the "nothing to be done" message only
  when INSTALL or REMOVE is non-empty.
* tests/guix-package.sh (readlink_base): New function.
  Add tests for `--roll-back'.
* doc/guix.texi (Invoking guix-package): Document `--roll-back'.

doc: Start documenting derivations.

* doc/guix.texi (Defining Packages): Add cross-reference to
  "Derivations".
  (The Store): Add `build-derivations'.
  (Derivations): Populate.

doc: Fix typos, and improve daemon documentation.

* doc/guix.texi: Fix typos.
  (Invoking guix-daemon): Add details about `--disable-log-compression'
  and `--disable-store-optimization'.
  Reported by Nikita Karetnikov <nikita@karetnikov.org>.

doc: Remove @documentlanguage.

* doc/guix.texi: Remove @documentlanguage, which confuses TeX.

doc: Start documenting (guix store).

* doc/guix.texi (The Store): Populate.
  (Introduction): Add cross-reference.  Change "package store" to "the
  store".