serialization: Check for EOF and incomplete input conditions.

Fixes <http://bugs.gnu.org/19756>.
Reported by <sleep_walker@suse.cz>.

* guix/serialization.scm (currently-restored-file): New variable.
  (get-bytevector-n*): New procedure.
  (read-int, read-long-long, read-string, read-latin1-string,
  read-contents): Use it instead of 'get-bytevector-n'.
  (restore-file): Parameterize 'currently-restored-file' and set it.
* tests/nar.scm ("restore-file with incomplete input"): New test.

doc: Document the location of the build directory.

Fixes <http://bugs.gnu.org/19771>.
Reported by Andrei Osipov <andrspv@gmail.com>.

* doc/guix.texi (Invoking guix-daemon): Document the build directory
  location.

gnu: gimp: Add EXIF and SVG support, plus color management.

* gnu/packages/gimp.scm (gimp)[inputs]: Add LIBEXIF, LCMS, and LIBRSVG.

gnu: podofo: Add optional input lua.

* gnu/packages/pdf.scm (podofo): Add optional input lua-5.1.

gnu: podofo: Update to 0.9.3.

* gnu/packages/pdf.scm (podofo): Update to 0.9.3.

gnu: podofo: Enable building a shared library.

* gnu/packages/pdf.scm (podofo): Enable building a shared library in addition
    to a static one.

gnu: chmlib: Correct license.

* gnu/packages/ebook.scm (chmlib): Correct copy-pasted license field.

gnu: Add chmlib.

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

gnu: dejagnu: Update to 1.5.2.

* gnu/packages/dejagnu.scm (dejagnu): Update to 1.5.2.

gnu: global: Update to 6.3.4.

* gnu/packages/global.scm (global): Update to 6.3.4.

gnu: eigen: Update to 3.2.4.

* gnu/packages/algebra.scm (eigen): Update to 3.2.4.

gnu: imagemagick: Update to 6.9.0-4.

* gnu/packages/imagemagick.scm (imagemagick): Update to 6.9.0-4.

gnu: tumbler: Update to 0.1.30.

* gnu/packages/xfce.scm (tumbler): Update to 0.1.30.  Use latest gstreamer.

gnu: wicd: Fix curses client to work with urwid 1.3.

* gnu/packages/patches/wicd-urwid-1.3.patch: New file.
* gnu-system (dist_patch_DATA): Add it.
* gnu/packages/wicd.scm (wicd): Add patch.

gnu: ntp: Update to 4.2.8p1.

* gnu/packages/ntp.scm (ntp): Update to 4.2.8p1.

gnu: slock: Update to 1.2

* gnu/packages/dwm.scm (slock): Update to 1.2

tests: Disable grafts when comparing derivations.

Fixes a regression introduced with the grafting of Patch in 3f11f01.

* tests/packages.scm ("reference to non-existent output"): Wrap in
  'parameterize'.

guix package: Make custom profiles actual indirect roots.

Before that, any profile generation built when '-p' is used would
effectively become a permanent GC root because the symlink in
/var/guix/gcroots/auto would point directly to /gnu/store/...-profile.

* guix/scripts/package.scm (maybe-register-gc-root): Rename to...
  (register-gc-root): ... this.  Remove conditional, and replace call to
  'canonicalize-path' with (string-append (getcwd) "/" ...).
  (guix-package): Call 'register-gc-root' only if PROFILE is different
  from %CURRENT-PROFILE.
* tests/guix-package.sh: Add test case.

pull: Always install the ~/.config/guix/latest symlink.

Before that, if two users on the same machine ran 'guix pull', the
second one would have the "Guix already up to date" message and their
~/.config/guix/latest link would be left unchanged---effectively
preventing them from updating.

* guix/scripts/pull.scm (build-and-install): Install the 'latest'
  symlink regardless of whether TO-DO? is true or false.

doc: Provide a better illustration of Ethernet interface names.

Reported on #guix.

* doc/guix.texi (System Installation)[USB Stick Installation]: Mention
  "eno1" instead of "eth0" and give other examples.