gnu: python: Build the tkinter module.

Fixes <http://bugs.gnu.org/20889>.
Reported by Federico Beffa <beffa@ieee.org>.

* gnu/packages/python.scm (python-2)[arguments]: Pass
  --with-tcltk-includes and --with-tcltk-libs.
  [inputs]: Add TCL and TK.

gnu: python: Add "minimal" variants.

* gnu/packages/python.scm (python2-minimal, python-minimal): New
  variables.
  (wrap-python3): New procedure.
  (python-wrapper): Use it.
  (python-minimal-wrapper): New variable.
* gnu/packages/xml.scm (libxslt)[native-inputs]: Use
  PYTHON-MINIMAL-WRAPPER instead of PYTHON-WRAPPER.
* gnu/packages/xorg.scm (xcb-proto, libxcb, xorg-server): Likewise.

gnu: python-wrapper: Improve synopsis and description.

* gnu/packages/python.scm (python-wrapper): Add 'synopsis' field; provide
  literal 'description' value.

gnu: python: Do not retain references to build tools.

* gnu/packages/python.scm (python-2)[arguments]: Add
  'do-not-record-configure-flags' and
  'do-not-record-configure-flags-in-makefile' phases.

Use "normalized codesets" everywhere.

In other words, change "xx_YY.UTF-8" to "xx_YY.utf8".

* guix/profiles.scm (ca-certificate-bundle): Use "en_US.utf8" instead of
  "en_US.UTF-8".
* guix/packages.scm (patch-and-repack): Likewise.
* guix/build/gnu-build-system.scm (install-locale): Likewise.
* guix/build-system/gnu.scm (gnu-build, gnu-cross-build): Likewise.
* gnu/packages/python.scm (python-ipython): Likewise.
* gnu/packages/gawk.scm (gawk): Likewise.
* build-aux/hydra/demo-os.scm: Likewise.
* gnu/packages/guile.scm (guile-ncurses)[arguments]: Remove
  'change-locale' phase.

Merge branch 'core-updates'

gnu: Add pyOpenSSL.

* gnu/packages/python.scm (python-pyopenssl, python2-pyopenssl): New
  variables.

gnu: Add python-cryptography.

* gnu/packages/python.scm (python-cryptography, python2-cryptography):
  New variables.

gnu: Add python-cryptography-vectors.

* gnu/packages/python.scm (python-cryptography-vectors,
  python2-cryptography-vectors): New variables.

gnu: Add python-pretend.

* gnu/packages/python.scm (python-pretend, python2-pretend): New
  variables.

gnu: Add python-idna.

* gnu/packages/python.scm (python-idna, python2-idna): New variables.

gnu: Add python-ipaddress.

* gnu/packages/python.scm (python2-ipaddress): New variable.

Merge branch 'master' into core-updates

gnu: Add python-pyasn1.

* gnu/packages/python.scm (python-pyasn1, python2-pyasn1): New
  variables.

gnu: python-cffi: Update to 1.2.1.

* gnu/packages/python.scm (python-cffi): Update to 1.2.1.
  [native-inputs]: Add python-pytest.
  [arguments]: Enable tests.

Merge branch 'master' into core-updates

gnu: python2-ipython: Override terminado in propagated inputs.

* gnu/packages/python.scm (python2-ipython)[inputs, propagated-inputs]:
  Override inherited "python-terminado" in propagated inputs instead of
  regular inputs.

gnu: Add python2-keyring.

* gnu/packages/python.scm (python2-keyring): New variable.

gnu: Add python2-pyflakes and fix python2-pyflakes-0.8.1.

* gnu/packages/python.scm (python2-pyflakes): New variable.
* gnu/packages/python.scm (python2-pyflakes-0.8.1): Fix the definition.

gnu: Add python-prettytable

* gnu/packages/python.scm (python-prettytable,
  python2-prettytable): New variables.