Add a preliminary `guix-package' command-line tool.

* guix-package.in, tests/guix-package.sh: New files.
* configure.ac: Output `guix-package'.
* Makefile.am (TESTS): Add `tests/guix-package.sh'.
  (bin_SCRIPTS): Add `guix-package'.

store: Add `store-path-package-name'.

* guix/store.scm (store-path-package-name): New procedure.
* tests/utils.scm ("store-path-package-name"): New test.

utils: Remove stuff committed by error.

This was wrongfully committed in df1fab58.

* guix/utils.scm (hash-set-proc, hash-ref*, memoizing-lambda): Remove.

build: Add unit test for the `guix-build' command.

* tests/guix-build.sh: New file.
* Makefile.am (TESTS): Add it.
  (LOG_COMPILER): Rename to...
  (SCM_LOG_COMPILER): ... this.  Move flags to...
  (AM_SCM_LOG_FLAGS): ... this.
  (TEST_EXTENSIONS, SH_LOG_COMPILER, AM_SH_LOG_FLAGS): New variables.

Add (guix ui).

* guix/ui.scm: New file.
* Makefile.am (MODULES): Add it.
* po/POTFILES.in: Add it.

* guix-build.in: Use it.
  (_, N_, leave): Remove.
  (guix-build): Use `with-error-handling' instead of the `guard' form.
* guix-download.in: Use it.
  (_, N_, leave): Remove.

build-system/gnu: Distinguish between imported modules and used modules.

* guix/build-system/gnu.scm (gnu-build): Add the `imported-modules'
  keyword parameter.  Pass it to `build-expression->derivation'.

release.nix: Use `--no-substitutes' in `distro.hello'.

* release.nix (distro.hello): Use `guix-build --no-substitutes', to
  avoid failures due to unavailable stale substitutes on
  hydra.nixos.org.

guix-build: Add `--root'.

* guix/store.scm (add-indirect-root): New operation.
* guix-build.in (show-help): Document `--root'.
  (%options): Add `--root'.
  (guix-build)[register-root]: New procedure.  Call it when `--root' is
  passed.

Add (guix build union).

* guix/build/union.scm, tests/union.scm: New files.
* Makefile.am (MODULES): Add `guix/build/union.scm'.
  (TESTS): Add `tests/union.scm'.

release.nix: Change `distro.hello' to produce something.

* release.nix (distro.hello)[buildPhase]: Tee the log to $out.  Add a
  `name' attribute; remove `buildInputs' and instead use the full path
  to `guix-build'.

distro: Build Bash sequentially.

* distro/packages/base.scm (bash): Set `#:parallel-build?' and
  `#:parallel-tests?' to #f.

tests: Use our own bootstrap tools.

* tests/builders.scm (%bootstrap-inputs): Use %BOOT0-INPUTS from the distro.
* tests/packages.scm (%bootstrap-inputs): Likewise.
* tests/derivations.scm (%coreutils): Alias for %BOOTSTRAP-COREUTILS&CO.

release.nix: Add a `distro.hello' job.

* release.nix (distro.hello): New job.

build: Preserve the executable bit of bootstrap binaries.

* Makefile.am (install-data-hook): New target.

build: Make sure scripts know where to find their modules.

* guix-build.in, guix-download.in: Define `prefix' and `datarootdir', so
  that `guilemoduledir' expands to something meaningful.

release.nix: Pre-download the Guile bootstrap tarball.

* release.nix (bootstrap_guile): New variable.
  (build)[preBuild]: New attribute.

build: Fix out-of-source-tree builds.

* Makefile.am (distro/packages/bootstrap/x86_64-linux/guile-bootstrap-2.0.6.tar.xz,
  distro/packages/bootstrap/i686-linux/guile-bootstrap-2.0.6.tar.xz):
  Make the target's parent directory.
* pre-inst-env.in (DISTRO_BOOTSTRAP_PATH): Add the builddir-relative
  directory.

distro: Change $DISTRO_{PATCH,BOOTSTRAP}_DIRECTORY to search paths.

* distro.scm (not-colon): New variable.
  (%patch-directory): Rename to...
  (%patch-path): ... this.  Turn into a list.  Expect $DISTRO_PATCH_PATH
  to be a colon-separated search path.
  (%bootstrap-binaries-directory): Rename to...
  (%bootstrap-binaries-path): ... this.  Likewise.
  (search-patch, search-bootstrap-binary): Adjust accordingly.

* pre-inst-env.in: Change to use `DISTRO_PATCH_PATH' and
  `DISTRO_BOOTSTRAP_PATH'.

release.nix: Set succeed-on-failure and build-out-source-tree.

* release.nix: Define `succeedOnFailure', `keepBuildDirectory', and
  `buildOutOfSourceTree'.
  (build): Inherit them.

build: Move `distro/patches' to `distro/packages/patches'.

* distro/patches: Move directory to...
* distro/packages/patches: ... here.
* Makefile.am (dist_patch_DATA): Adjust accordingly.
* pre-inst-env.in (DISTRO_PATCH_DIRECTORY): Likewise.