gnu: Fix or update a number of 'home-page' fields.

* gnu/packages/fltk.scm (fltk): Fix 'home-page'.
* gnu/packages/fonts.scm (font-bitstream-vera): Likewise, and fix
  license URL.
* gnu/packages/games.scm (gnubg, cmatrix, chess): Fix 'home-page'.
* gnu/packages/kde.scm (attica): Likewise.
* gnu/packages/mail.scm (fetchmail): Likewise.
* gnu/packages/popt.scm (popt): Likewise.
* gnu/packages/python.scm (python-mock): Likewise.
* gnu/packages/stalonetray.scm (stalonetray): Likewise.

gnu: Add pysam.

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

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

Revert "gnu: matplotlib: Comment out python2-matplotlib."

This reverts commit afc720d34c43a2fcf0b5871226c15ad6c5f73697.

gnu: matplotlib: Comment out python2-matplotlib.

* gnu/packages/python.scm (python2-matplotlib, python2-scipy, python2-numpy):
  Comment out python2-matplotlib and the packages making use of it as the
  generation of the derivation of these packages takes very long.

gnu: cairocffi: Move to python module.

* gnu/packages/gtk.scm, gnu/packages/python.scm (python-cairocffi,
  python2-cairocffi): Move variables from gtk to python module to avoid
  circular dependency.

Reported by Mark H Weaver <mhw@netris.org>

gnu: matplotlib: Add gtk3 backends and optional dependency.  Adjust inputs.

* gnu/packages/python.scm (python-matplotlib, python2-matplotlib): Add gtk3
  backends with the necessary inputs and a 'configure-environment' phase.  Add
  the optional 'python-pillow' dependency.  Move 'python-pyparsing' from
  'inputs' to 'propagated-inputs' as it is required at run time.

gnu: Add xcffib

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

Revert "gnu: python-numpy-bootstrap: Reduce matrix size in failing test."

This reverts commit 31557440c29f8d93b366422bfec4dab341eff79f as it did not
provide the desired effect.  The test is still failing.

gnu: python-numpy-bootstrap: Reduce matrix size in failing test.

* gnu/packages/python.scm (python-numpy-bootstrap): Add phase
  'fix-failing-tests.

gnu: python-numpy-bootstrap: Make tests verbose.

* gnu/packages/python.scm (python-numpy-bootstrap): Make tests verbose to
  allow test failure debugging on hydra.

gnu: Add cffi.

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

gnu: Add pycparser.

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

gnu: Add scipy.

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

gnu: Add python-pycairo.

* gnu/packages/gtk.scm (python-pycairo, python2-py2cairo): New variables.

gnu: Add python-elib.intl.

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

gnu: Add python-distutils-extra.

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

gnu: Add python-pillow.

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

gnu: Add python-sqlalchemy.

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

gnu: python: Add sqlite input.

* gnu/packages/patches/python-sqlite-3.8.4-test-fix.patch,
  gnu/packages/patches/python2-sqlite-3.8.4-test-fix.patch: New patches.
* gnu-system.am (dist_patch_DATA): Add them.
* gnu/packages/python.scm (python-2)[source]: Add patch.
  [inputs]: Add sqlite.
  (python)[source]: Add patch.

gnu: Add numpy.

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