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.

build: Pass the appropriate flags when building `libstore.a'.

* daemon.am (libstore_a_CFLAGS): Rename to...
  (libstore_a_CXXFLAGS): ... this.

gnu: shishi: Update to 1.0.2.

* gnu/packages/shishi.scm (shishi): Update to 1.0.2.
* gnu/packages/patches/shishi-gets-undeclared.patch: Remove it.
* Makefile.am (dist_patch_DATA): Adjust accordingly.

gnu: Python: fix the compilation of some modules from the standard library.

This commit enables the bz2, dbm, readline, ssl and zlib modules.

* gnu/packages/gdbm.scm: Enable the compatibility mode.
* gnu/packages/python.scm: Enable a few modules from the standard library.
* gnu/packages/patches/python-fix-dbm.patch: New file.
* Makefile.am: Add it.

Add (guix nar) and (guix serialization).

* guix/store.scm (write-int, read-int, write-long-long, read-long-long,
  write-padding, write-string, read-string, read-latin1-string,
  write-string-list, read-string-list, write-store-path,
  read-store-path, write-store-path-list, read-store-path-list): Move to
  serialization.scm.
  (write-contents, write-file): Move to nar.scm.
* guix/nar.scm, guix/serialization.scm: New files.
* Makefile.am (MODULES): Add them.

substitute-binary: Fix communication of several store paths to the daemon.

* guix/scripts/substitute-binary.scm (guix-substitute-binary)["--query"]:
  Emit blank lines only after the complete list of store paths has been
  returned.

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.

gnu: bigloo: Add dependencies on Avahi and libphidget.

* gnu/packages/scheme.scm (bigloo): Add Avahi and libphidget as inputs,
  and pkg-config as a native input.

gnu: Add libphidget.

* gnu/packages/libphidget.scm: New file.
* Makefile.am (MODULES): Add it.

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.

gnu-maintenance: Adjust `http-fetch' to the various Guile versions.

* guix/gnu-maintenance.scm (http-fetch): Try #:streaming? #t, or
  'http-get*', or 'http-get' as a last resort.  Check whether DATA is
  #f, a string, or an input port.

pull: Switch to the cgit URL.

* guix/scripts/pull.scm (%snapshot-url): Switch to the cgit URL, given
  that the Hydra one is not currently available.

gnu: perl-xml-parser: Fix URL.

* gnu/packages/xml.scm (perl-xml-parser): Fix URL.

snix: Adjust import to current Nixpkgs input attribute names.

* guix/snix.scm (snix-derivation->guix-package): Use the new names
  `nativeBuildInputs' and `propagatedNativeBuildInputs'.

gnu-maintenance: Improve 'official-gnu-packages'; add related procedures.

* guix/gnu-maintenance.scm (http-fetch): Return an input port.
  (<gnu-package-descriptor>): Add it.
  (official-gnu-packages): Use <gnu-package-descriptor>.
  (find-packages): Add it.
  (gnu-package?): Adjust accordingly.

Add (guix build-system cmake).

* guix/build/cmake-build-system.scm, guix/build-system/cmake.scm: New files.
* Makefile.am (MODULES): Add them.

build: Set `%fresh-auto-compile' in `hydra.scm'.

* hydra.scm: Set `%fresh-auto-compile' to #t.

gnu: make-bootstrap: Import (gnu packages gcc).

* gnu/packages/make-bootstrap.scm: Import (gnu packages gcc).

download: Remove unreliable GNU mirror.

* guix/download.scm (%mirrors)[gnu]: Remove ftp.chg.ru.

gnu: Add libelf.

* gnu/packages/gcc.scm (libelf): New variable.