gnu: Add lsof.

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

gnu: Add Perl XML::Parser.

* gnu/packages/xml.scm (perl-xml-parser): New variable.

Add (guix build-system perl).

* guix/build-system/perl.scm, guix/build/perl-build-system.scm: New files.
* Makefile.am (MODULES): Add them.
* guix/build-system/gnu.scm (standard-inputs): Make public.

download: Add CPAN mirrors.

* guix/download.scm (%mirrors)[cpan]: New URLs.

gnu: Add vpnc.

* gnu/packages/vpn.scm: New file.
* Makefile.am (MODULES): Add it.
* gnu/packages/patches/vpnc-script.patch: New file.
* Makefile.am (dist_patch_DATA): Add it.

release.nix: Reduce the number of dependencies.

* release.nix (tarball): Use a minimal Git.

gnu: Add libdaemon.

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

release.nix: Unchroot recursively.

* release.nix (unchroot): Operate recursively on build inputs.

release.nix: Build outside of a chroot.

* release.nix (unchroot): New function.
  (jobs)[tarball, build, build_disable_daemon]: Use it.

ui: Factorize `read/eval-package-expression'.

* guix/scripts/package.scm (read/eval-package-expression): Move to...
* guix/ui.scm (read/eval-package-expression): ... here.
* guix/scripts/build.scm (derivations-from-package-expressions): Use it.

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'.

gnu: global: Update to 6.2.8.

* gnu/packages/global.scm (global): Update to 6.2.8.

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.

download: Add X.org mirrors.

* guix/download.scm (%mirrors): Add `xorg'.

gnu: screen: Use GNU mirror.

* gnu/packages/screen.scm (screen): Use GNU mirror.

gnu: Update libpng to 1.5.14.

* gnu/packages/libpng.scm (libpng): Switch to version 1.5.14.

pull: Distinguish "already up to date" from "updated".

* guix/ui.scm (show-what-to-build): Return (length req*).
* guix/scripts/pull.scm (guix-pull): Print an "already up to date"
  message when there's nothing to build.

pull: Build (guix build download) first, because of the (gnutls) autoload.

* guix/scripts/pull.scm (unpack): Build (guix build download) first, as
  done in 855a8ad71def2ebc594ed32c57bda0ca4e13d91c.
  Reported by Andreas Enge <andreas@enge.fr>.

guix: Make sure UPDATES-DIR is valid.

* scripts/guix.in: Make sure UPDATES-DIR is not #f.