gnu: obs: Update to 18.0.1.

* gnu/packages/video.scm (obs): Update to 18.0.1.

gnu: youtube-dl: Update to 2017.03.15.

* gnu/packages/video.scm (youtube-dl): Update to 2017.03.15.

gnu: stress-make: Fix description.

* gnu/packages/debug.scm (stress-make)[description]: Fix typo.
Avoid ambiguous use of ‘in order’.

gnu: znc: Update to 1.6.5.

* gnu/packages/messaging.scm (znc): Update to 1.6.5.

gnu: grue-hunter: Correctly install documentation.

* gnu/packages/games.scm (grue-hunter)[arguments]: Install and populate
‘/share/doc/grue-hunter’ as a directory, not a plain file.

gnu: samtools: End installation phases with truth.

* gnu/packages/bioinformatics.scm (samtools, samtools-0.1)[arguments]:
Return #T instead of the undefined results of COPY-FILE or INSTALL-FILE.

gnu: w3m: Update to 0.5.3+git20170102 [security fixes].

See 'NEWS' and 'ChangeLog' in the source distribution for more
information about the security-related bug fixes.

* gnu/packages/w3m.scm (w3m): Update to 0.5.3+git20170102.

Revert "gnu: gitolite: Fix shebangs in hooks."

This change embedded store references in the shebangs of scripts that
were meant to be copied out of the store. Those scripts would break when
the interpreters expected by the shebangs were garbage collected.

<https://debbugs.gnu.org/cgi/bugreport.cgi?bug=25966#28>

This reverts commit d0c16adb190c7244ee3ef1329cba78a015ae5d10.

Revert "gnu: nss: Use 'modify-phases' syntax."

This reverts commit 87f1c7efc18f8996b0b2817a5f7b84eebe2ddf5a.

Revert "gnu: nss, nss-certs: Update to 3.29.3."

Hydra failed to build this version. See discussion at
https://lists.gnu.org/archive/html/guix-devel/2017-03/msg00408.html.

This reverts commit 4f3dcdd99ba13ab3bdbf1e014afcd076cd95fac7.

gnu: Add ocaml-ppx-typerep-conv.

* gnu/packages/ocaml.scm (ocaml-ppx-typerep-conv): New variable.

gnu: Add ocaml-ppx-let.

* gnu/packages/ocaml.scm (ocaml-ppx-let): New variable.

gnu: Add ocaml-ppx-enumerate.

* gnu/packages/ocaml.scm (ocaml-ppx-enumerate): New variable.

gnu: Add ocaml-ppx-assert.

* gnu/packages/ocaml.scm (ocaml-ppx-assert): New variable.

gnu: Add ocaml-ppx-here.

* gnu/packages/ocaml.scm (ocaml-ppx-here): New variable.

gnu: Add ocaml-ppx-variants-conv.

* gnu/packages/ocaml.scm (ocaml-ppx-variants-conv): New variable.

gnu: Add ocaml-ppx-sexp-conv.

* gnu/packages/ocaml.scm (ocaml-ppx-sexp-conv): New variable.

gnu: Add ocaml-variantslib.

* gnu/packages/ocaml.scm (ocaml-variantslib): New variable.

gnu: Add ocaml-typerep.

* gnu/packages/ocaml.scm (ocaml-typerep): New variable.

gnu: Add ocaml-sexplib.

* gnu/packages/ocaml.scm (ocaml-sexplib): New variable.