doc: Mention Linux containers; emphasize reproducible builds.

* doc/guix.texi (Introduction): Use "containers" instead of "chroots".
  (Invoking guix-daemon): Add @cindex entries.  Mention the Linux
  container features.
  (Features): Add sentence on build reproducibility.

doc: Improve "Installing Guix from Guix" section.

Reported by Mark H. Weaver <mhw@netris.org>.

* README (Installing Guix from Guix): Explicitly mention $PATH
  separately.  Mention $ACLOCAL_PATH, not $ACLOCAL.  Give the exact
  command to install the dependencies.  Remove mention of
  $GUIX_LD_WRAPPER_ALLOW_IMPURITIES, which is no longer needed.

gnu: cflow: Install Emacs mode.

* gnu/packages/cflow.scm (cflow): Add Emacs as an input.

substitute-binary: Adjust timeout handling for Guile > 2.0.9.

* guix/scripts/substitute-binary.scm (with-timeout): Update comment to
  mention the fix's commit ID.
  (fetch): In the 'with-timeout' handler, close PORT only one Guile
  versions < 2.0.9.39.  Before that, on Guile >= 2.0.9.39, the HTTP
  client would end up trying to read from a closed file descriptor.

derivations: Allow 'map-derivations' to replace sources.

* guix/derivations.scm (map-derivation)[input->output-paths]: Allow
  non-derivation inputs.
  Allow replacements to be store files.  Replace in SOURCES too.
* tests/derivations.scm ("map-derivation, sources"): New test.

packages: Suitably cope with indirect store paths as package sources.

* guix/packages.scm (package-source-derivation): Don't let indirect
  store paths pass through.
* tests/packages.scm ("package-source-derivation, indirect store path"):
  New test.

store: Make 'direct-store-path?' public.

* guix/store.scm (direct-store-path?): New procedure.
* guix/derivations.scm (derivation)[direct-store-path?]: Remove.
* tests/store.scm ("direct-store-path?"): New test.

derivations: Add 'map-derivation'.

* guix/derivations.scm (map-derivation): New procedure.
* tests/derivations.scm ("map-derivation"): New test.

utils: Add 'string-replace-substring'.

* guix/utils.scm (string-replace-substring): New procedure.  Based on
  code by Mark H. Weaver.
* tests/utils.scm ("string-replace-substring"): New test.

gnu: Add IceCat.

* gnu/packages/gnuzilla.scm: New file.
* gnu-system.am (GNU_SYSTEM_MODULES): Add it.

gnu: Add GNU APL.

* gnu/packages/apl.scm: New file.
* gnu-system.am (GNU_SYSTEM_MODULES): Add it.

guix build: Add '--log-file'.

* guix/scripts/build.scm (show-help): Add '--log-file'.
  (%options): Likewise.
  (guix-build): Set %FILE-PORT-NAME-CANONICALIZATION.  Honor '--log-file'.
* tests/guix-build.sh: Add '--log-file' tests.
* doc/guix.texi (Invoking guix build): Document '--log-file'.

store: Add 'log-file' procedure.

* guix/store.scm (log-file): New procedure.
* tests/store.scm ("log-file, derivation", "log-file, output file
  name"): New tests.

gnu: Add phonon.

* gnu/packages/kde.scm (phonon): New variable.

gnu: qt: Enable SIMD instructions available on x86_64.

* gnu/packages/qt.scm (qt, qt-4): Enable mmx, 3dnow, sse and sse2 on x86_64.

gnu: Add GVPE.

* gnu/packages/gvpe.scm: New file.
* gnu-system.am (GNU_SYSTEM_MODULES): Add it.

gnu: Add GNU complexity.

* gnu/packages/complexity.scm: New file.
* gnu-system.am (GNU_SYSTEM_MODULES): Add it.

nls: Add Serbian translation.

* po/sr.po: New file.
* po/LINGUAS: Add 'sr'.

substitute-binary: Increase lookup concurrency to reduce latency.

* guix/scripts/substitute-binary.scm (%lookup-threads): New variable.
  (guix-substitute-binary): Use 'n-par-map' instead of 'par-map' for
  batch 'lookup-narinfo' calls.

gnu: lapack: Use origin snippet to remove the non-free files.

* gnu/packages/maths.scm (lapack): Add 'snippet' field with contents of
  former 'remove-non-free-files' phase; remove that phase.