gnu: Remove duplicates from (gnu packages statistics).

* gnu/packages/statistics.scm (r-cluster, r-codetools, r-kernsmooth): Remove
duplicates.

gnu: Move testing packages from python.scm to check.scm.

* gnu/packages/python.scm (python-behave-web-api, python2-behave-web-api,
python-mock, python2-mock, python-mock-2, python-nose, python2-nose,
python-nose2, python2-nose2, python-unittest2, python2-unittest2,
python-pytest, python2-pytest, python-pytest-3.0, python2-pytest-3.0,
python-pytest-cov, python2-pytest-cov, python-pytest-runner,
python2-pytest-runner, python-pytest-mock, python2-pytest-mock,
python-pytest-xdist, python2-pytest-xdist, python-scripttest,
python2-scripttest, python-testtools, python2-testtools, python-testscenarios,
python2-testscenarios, python-testresources, python2-testresources,
python-subunit, python2-subunit, python-fixtures, python2-fixtures,
python-testrepository, python2-testrepository, python-coverage,
python2-coverage, python-cov-core, python2-cov-core, python-testpath,
python2-testpath, python-testlib, python2-testlib, python-pytest-cache,
python2-pytest-cache, python-pytest-localserver, python-pytest-xprocess,
python-pytest-subtesthack, python2-pytest-subtesthack, python-hypothesis,
python2-hypothesis, python-lit, python2-lit, python-pytest-pep8,
python2-pytest-pep8, python-pytest-flakes, python2-pytest-flakes,
python2-coverage-test-runner, python-pylint, python2-pylint,
python-paramunittest, python2-python-paramunittest, python-pytest-warnings,
python2-pytest-warnings, python-pytest-capturelog, python2-pytest-capturelog,
python-pytest-catchlog, python2-pytest-catchlog, python-nosexcover,
python2-nosexcover, python-discover, python2-discover, behave, python-rednose,
python2-rednose, python-nose-randomly, python2-nose-randomly,
python-nose-timer, python2-nose-timer): Move from here...
* gnu/packages/check.scm: ...to here.
* gnu/packages/admin.scm,
gnu/packages/android.scm,
gnu/packages/backup.scm,
gnu/packages/bioinformatics.scm,
gnu/packages/calendar.scm,
gnu/packages/dav.scm,
gnu/packages/django.scm,
gnu/packages/freedesktop.scm,
gnu/packages/haskell.scm,
gnu/packages/image.scm,
gnu/packages/irc.scm,
gnu/packages/jrnl.scm,
gnu/packages/ldc.scm,
gnu/packages/libffi.scm,
gnu/packages/mail.scm,
gnu/packages/mpd.scm,
gnu/packages/openstack.scm,
gnu/packages/package-management.scm,
gnu/packages/password-utils.scm,
gnu/packages/python-crypto.scm,
gnu/packages/python-web.scm,
gnu/packages/rdf.scm,
gnu/packages/statistics.scm,
gnu/packages/storage.scm,
gnu/packages/time.scm,
gnu/packages/tls.scm,
gnu/packages/tor.scm,
gnu/packages/tryton.scm: Adjust accordingly.

gnu: Add r-directlabels.

* gnu/packages/statistics.scm (r-directlabels): New variable.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

gnu: r-prabclus: Update description.

* gnu/packages/statistics.scm (r-prabclus)[description]: Fix grammar errors.

gnu: r-fdrtool: Update description.

* gnu/packages/statistics.scm (r-fdrtool)[description]: Use "@dfn" syntax.

gnu: r-tidyselect: Update to 0.2.3.

* gnu/packages/statistics.scm (r-tidyselect): Update to 0.2.3.

gnu: r-lubridate: Update to 1.7.1.

* gnu/packages/statistics.scm (r-lubridate): Update to 1.7.1.
[propagated-inputs]: Add r-rcpp.

gnu: r-preprocesscore: Update to 1.40.0.

* gnu/packages/statistics.scm (r-preprocesscore): Update to 1.40.0.

gnu: r-r-utils: Update to 2.6.0.

* gnu/packages/statistics.scm (r-r-utils): Update to 2.6.0.

gnu: r-openssl: Update to 0.9.8.

* gnu/packages/statistics.scm (r-openssl): Update to 0.9.8.

gnu: r-rlang: Update to 0.1.4.

* gnu/packages/statistics.scm (r-rlang): Update to 0.1.4.

gnu: r-withr: Update to 2.1.0.

* gnu/packages/statistics.scm (r-withr): Update to 2.1.0.
[propagated-inputs]: Add r-lattice.

gnu: r-quantreg: Update to 5.34.

* gnu/packages/statistics.scm (r-quantreg): Update to 5.34.

gnu: r-robustbase: Update to 0.92-8.

* gnu/packages/statistics.scm (r-robustbase): Update to 0.92-8.

gnu: r-purrr: Update to 0.2.4.

* gnu/packages/statistics.scm (r-purrr): Update to 0.2.4.

gnu: r-irlba: Update to 2.3.1.

* gnu/packages/statistics.scm (r-irlba): Update to 2.3.1.

gnu: r-checkmate: Update to 1.8.5.

* gnu/packages/statistics.scm (r-checkmate): Update to 1.8.5.

gnu: r-multitaper: Update to 1.0-14.

* gnu/packages/statistics.scm (r-multitaper): Update to 1.0-14.

gnu: r-data-table: Update to 1.10.4-3.

* gnu/packages/statistics.scm (r-data-table): Update to 1.10.4-3.

gnu: r-pryr: Update to 0.1.3

* gnu/packages/statistics.scm (r-pryr): Update to 0.1.3.