ENH: ship six 1.9.0

Six seems to be the external dependency that is most likely to cause
problems, and it is a small standalone .py file that is designed for
projects to ship in their source tree.

Shipping has the following advantages:

* Reduces pip dependencies by one;
* Makes mpl less vulnerable to upstream changes in six.  At present, it
  is possible for six to change upstream in pypi and break matplotlib
  installs, requiring a new mpl release;

It does mean that we don't get the lastest six, but I believe this is an
advantage for the reason above.  Now we are so far into the Python 3
era, six should be rather stable.

lib/matplotlib/__init__.py

@@ -102,7 +102,7 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
+from matplotlib.externals import six
 import sys
 import distutils.version
 from itertools import chain
@@ -124,8 +124,8 @@
                                 validate_backend)
 
 import numpy
-from six.moves.urllib.request import urlopen
-from six.moves import reload_module as reload
+from matplotlib.externals.six.moves.urllib.request import urlopen
+from matplotlib.externals.six.moves import reload_module as reload
 
 __version__ = str('1.5.dev1')
 __version__numpy__ = str('1.6')  # minimum required numpy version

lib/matplotlib/_mathtext_data.py

@@ -6,7 +6,7 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
+from matplotlib.externals import six
 
 """
 from matplotlib.ft2font import FT2Font

lib/matplotlib/_pylab_helpers.py

@@ -4,7 +4,7 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
+from matplotlib.externals import six
 import sys
 import gc
 import atexit

lib/matplotlib/afm.py

@@ -36,8 +36,8 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
-from six.moves import map
+from matplotlib.externals import six
+from matplotlib.externals.six.moves import map
 
 import sys
 import os

lib/matplotlib/animation.py

@@ -20,8 +20,8 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
-from six.moves import xrange, zip
+from matplotlib.externals import six
+from matplotlib.externals.six.moves import xrange, zip
 
 import platform
 import sys

lib/matplotlib/artist.py

@@ -1,7 +1,7 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
+from matplotlib.externals import six
 
 import re
 import warnings

lib/matplotlib/axes/_axes.py

@@ -1,8 +1,8 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
-from six.moves import reduce, xrange, zip, zip_longest
+from matplotlib.externals import six
+from matplotlib.externals.six.moves import reduce, xrange, zip, zip_longest
 
 import math
 import warnings

lib/matplotlib/axes/_base.py

@@ -1,8 +1,8 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
-from six.moves import xrange
+from matplotlib.externals import six
+from matplotlib.externals.six.moves import xrange
 
 import itertools
 import warnings

lib/matplotlib/axes/_subplots.py

@@ -1,8 +1,8 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
-from six.moves import map
+from matplotlib.externals import six
+from matplotlib.externals.six.moves import map
 
 from matplotlib.gridspec import GridSpec, SubplotSpec
 from matplotlib import docstring

lib/matplotlib/axis.py

@@ -4,7 +4,7 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
+from matplotlib.externals import six
 
 from matplotlib import rcParams
 import matplotlib.artist as artist

lib/matplotlib/backend_bases.py

@@ -35,8 +35,8 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
-from six.moves import xrange
+from matplotlib.externals import six
+from matplotlib.externals.six.moves import xrange
 
 import os
 import sys

lib/matplotlib/backend_managers.py

@@ -6,7 +6,7 @@
 
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
-import six
+from matplotlib.externals import six
 import warnings
 
 import matplotlib.cbook as cbook

lib/matplotlib/backend_tools.py

@@ -17,7 +17,7 @@
 import matplotlib.cbook as cbook
 from weakref import WeakKeyDictionary
 import numpy as np
-import six
+from matplotlib.externals import six
 
 
 class Cursors(object):

lib/matplotlib/backends/__init__.py

@@ -1,7 +1,7 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
+from matplotlib.externals import six
 
 import matplotlib
 import inspect

lib/matplotlib/backends/backend_agg.py

@@ -22,7 +22,7 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
+from matplotlib.externals import six
 
 import threading
 import numpy as np

lib/matplotlib/backends/backend_cairo.py

@@ -21,7 +21,7 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
+from matplotlib.externals import six
 
 import os, sys, warnings, gzip
 

lib/matplotlib/backends/backend_cocoaagg.py

@@ -15,8 +15,8 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
-from six.moves import xrange
+from matplotlib.externals import six
+from matplotlib.externals.six.moves import xrange
 
 import os, sys
 

lib/matplotlib/backends/backend_gdk.py

@@ -1,7 +1,7 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
+from matplotlib.externals import six
 
 import math
 import os

lib/matplotlib/backends/backend_gtk.py

@@ -1,7 +1,7 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
+from matplotlib.externals import six
 
 import os, sys, warnings
 def fn_name(): return sys._getframe(1).f_code.co_name

lib/matplotlib/backends/backend_gtk3.py

@@ -1,7 +1,7 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
+from matplotlib.externals import six
 
 import os, sys
 def fn_name(): return sys._getframe(1).f_code.co_name

lib/matplotlib/backends/backend_gtk3agg.py

@@ -1,7 +1,7 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
+from matplotlib.externals import six
 
 import numpy as np
 import sys

lib/matplotlib/backends/backend_gtk3cairo.py

@@ -1,7 +1,7 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
+from matplotlib.externals import six
 
 from . import backend_gtk3
 from . import backend_cairo

lib/matplotlib/backends/backend_gtkagg.py

@@ -4,7 +4,7 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
+from matplotlib.externals import six
 
 import os
 

lib/matplotlib/backends/backend_gtkcairo.py

@@ -5,7 +5,7 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
+from matplotlib.externals import six
 
 import gtk
 if gtk.pygtk_version < (2,7,0):

lib/matplotlib/backends/backend_macosx.py

@@ -1,7 +1,7 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
+from matplotlib.externals import six
 
 import os
 import numpy

lib/matplotlib/backends/backend_mixed.py

@@ -1,7 +1,7 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
+from matplotlib.externals import six
 
 from matplotlib._image import frombuffer
 from matplotlib.backends.backend_agg import RendererAgg

lib/matplotlib/backends/backend_nbagg.py

@@ -7,7 +7,7 @@
 import json
 import io
 import os
-import six
+from matplotlib.externals import six
 from uuid import uuid4 as uuid
 
 import tornado.ioloop

lib/matplotlib/backends/backend_pdf.py

@@ -7,7 +7,7 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
+from matplotlib.externals import six
 
 import codecs
 import os
@@ -18,8 +18,8 @@
 import zlib
 
 import numpy as np
-from six import unichr
-from io import BytesIO
+from matplotlib.externals.six import unichr
+from matplotlib.externals.six import BytesIO
 
 from datetime import datetime
 from math import ceil, cos, floor, pi, sin

lib/matplotlib/backends/backend_pgf.py

@@ -1,7 +1,7 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
+from matplotlib.externals import six
 
 import math
 import os

lib/matplotlib/backends/backend_ps.py

@@ -5,8 +5,8 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
-from six.moves import StringIO
+from matplotlib.externals import six
+from matplotlib.externals.six.moves import StringIO
 
 import glob, math, os, shutil, sys, time
 def _fn_name(): return sys._getframe(1).f_code.co_name

lib/matplotlib/backends/backend_qt4.py

@@ -1,8 +1,8 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
-from six import unichr
+from matplotlib.externals import six
+from matplotlib.externals.six import unichr
 import os
 import re
 import signal

lib/matplotlib/backends/backend_qt4agg.py

@@ -4,7 +4,7 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
+from matplotlib.externals import six
 
 import os  # not used
 import sys

lib/matplotlib/backends/backend_qt5.py

@@ -1,12 +1,12 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
-import six
+from matplotlib.externals import six
 
 import os
 import re
 import signal
 import sys
-from six import unichr
+from matplotlib.externals.six import unichr
 
 import matplotlib
 

lib/matplotlib/backends/backend_qt5agg.py

@@ -4,7 +4,7 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
+from matplotlib.externals import six
 
 import sys
 import ctypes

lib/matplotlib/backends/backend_svg.py

@@ -1,9 +1,9 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
-from six.moves import xrange
-from six import unichr
+from matplotlib.externals import six
+from matplotlib.externals.six.moves import xrange
+from matplotlib.externals.six import unichr
 
 import os, base64, tempfile, gzip, io, sys, codecs, re
 

lib/matplotlib/backends/backend_template.py

@@ -65,7 +65,7 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
+from matplotlib.externals import six
 
 import matplotlib
 from matplotlib._pylab_helpers import Gcf