gnu: python-statsmodels: Fix tests.

* gnu/packages/statistics.scm (python-statsmodels): Add patch to fix tests.
(python2-statsmodels)[propagated-inputs]: Add python2-pytz.
* gnu/packages/patches/python-statsmodels-fix-tests.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.

gnu: gtk-doc: Disable parallel tests.

* gnu/packages/gtk.scm (gtk-doc)[arguments]: Disable parallel tests.

gnu: gtk-doc: Update to 1.25.

* gnu/packages/gtk.scm (gtk-doc): Update to 1.25.

gnu: python2-bz2file: Use python-2.

This is a followup to 124df723a0150e968910e34d5e94023b18901d0c.
Problem reported by Andreas Enge <andreas@enge.fr>.

* gnu/packages/python.scm (python2-bz2file)[arguments]: Use python-2.

gnu: qt: Update to 5.6.1-1.

* gnu/packages/qt.scm (qt): Update to 5.6.1-1.

Co-authored-by: David Craven <david@craven.ch>

gnu: qt: Use modify-phases syntax.

* gnu/packages/qt.scm (qt): Use modify-phases syntax.

gnu: qtbase: Modify .cmake files to enable modules in different packages.

* gnu/packages/qt.scm (qtbase)[arguments]: In the configure phase, modify
.cmake and .cmake.in files so that find_package honors CMAKE_PREFIX_PATH.

gnu: Add GCompris.

* gnu/packages/education.scm (gcompris): New variable.

Merge branch 'version-0.11.0'

gnu: Add discrover.

* gnu/packages/bioinformatics.scm (discrover): New variable.

Rename references to (gnu packages tcsh).

* gnu/packages/algebra.scm, gnu/packages/boost.scm,
gnu/packages/maths.scm, gnu/packages/tex.scm, gnu/packages/vim.scm:
Change broken references to module (gnu packages tcsh) to (gnu packages
shells).

doc: Fix typos.

* doc/guix.texi (Application Setup): Use @xref, not @pxref, when
starting a sentence.
(Scheduled Job Execution): Remove extra indent in example; fix typos.

doc: Update Texinfo HTML cross-reference file..

* doc/htmlxref.cnf: Add entries for 'find' and 'mcron'.

gnu: fxtract: Restrict to x86_64-linux.

* gnu/packages/bioinformatics.scm (fxtract)[supported-systems]: Restrict to
  x86_64-linux.

gnu: python-bz2file: Disable tests.

* gnu/packages/python.scm (python-bz2file)[arguments]: Disable
tests.
(python2-bz2file)[arguments]: New field.

gnu: mdadm: Build without '-Werror'

* gnu/packages/linux.scm (mdadm)[arguments]: Add 'remove-W-error'
phase.

gnu: guix: Update development snapshot.

* gnu/packages/package-management.scm (guix-devel): Update to 4420940.
(guix): Set to GUIX-DEVEL.

gnu: zsh: Move to shells.scm.

* gnu/packages/zsh.scm (zsh): Move from here ...
* gnu/packages/shells.scm (zsh): ... to here.
* gnu/packages/zsh.scm: Delete file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Remove zsh.scm.

gnu: tcsh: Move to shells.scm.

* gnu/packages/tcsh.scm (tcsh): Move from here ...
* gnu/packages/shells.scm (tcsh): ... to here.
* gnu/packages/tcsh.scm: Delete file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Remove tcsh.scm.

gnu: rc: Move to shells.scm.

* gnu/packages/rc.scm (rc): Move from here ...
* gnu/packages/shells.scm (rc): ... to here.
* gnu/packages/rc.scm: Delete file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Remove rc.scm.