Just because we may have found IPv6 DNS servers from /etc/resolv.conf
doesn't mean we should force IPv6 support.

Instead we should disable the IPv6 DNS servers if IPv6 is disabled.

Note: this will also result in any IPv6 servers specified on the command
line being silently ignored too.

Specifying an IPv6 subnet will still require IPv6 support.

Closes #74

Closes #73.

In some cases (see #43) it seems that some network configurations may
end up setting a skip on lo. As sshuttle adds rules that rely on
filtering/translating packets on lo, this causes problem. This fix
overrides the skip and makes the rules be applied again.
Should fix at least some of the problems reported on #43.

This will make it easier to support other platforms/versions in the
future, e.g., OpenBSD.

This is the error message that this commit fixes:
TypeError: sequence item 142: expected a bytes-like object, str found

Complete what 1c46f25e started, more or less.

Closes: #68

Wew were trying to allocate an IPv6 socket even though we weren't using
IPv6, causing failures on systems without IPv6 support available.

This change means a number of methods on MultiListener, e.g. setsockopt,
should not be called until after the bind call.

Closes #68

Closes: #65

And some subtle grammar.

Closes: #66

Copied from https://coderwall.com/p/adfxgw/sshuttle-on-windows

Closes #64

It is autogenerated.

Closes #60.

Suspect it is causing sphinx to crash on readthedocs. See
https://github.com/sphinx-doc/sphinx/issues/1871

Not required as we are not documenting the source code.

See #60

this should also be backwards compatible with python 2

Fix the following error. Looks like we have to have a function to call
for the entrypoint.

$ pip install dist/sshuttle-0.76.dev8_ngf59508f4-py2-none-any.whl
Processing ./dist/sshuttle-0.76.dev8_ngf59508f4-py2-none-any.whl
Installing collected packages: sshuttle
Exception:
Traceback (most recent call last):
  File "/tmp/ddd/local/lib/python2.7/site-packages/pip/basecommand.py", line 211, in main
    status = self.run(options, args)
  File "/tmp/ddd/local/lib/python2.7/site-packages/pip/commands/install.py", line 311, in run
    root=options.root_path,
  File "/tmp/ddd/local/lib/python2.7/site-packages/pip/req/req_set.py", line 646, in install
    **kwargs
  File "/tmp/ddd/local/lib/python2.7/site-packages/pip/req/req_install.py", line 803, in install
    self.move_wheel_files(self.source_dir, root=root)
  File "/tmp/ddd/local/lib/python2.7/site-packages/pip/req/req_install.py", line 998, in move_wheel_files
    isolated=self.isolated,
  File "/tmp/ddd/local/lib/python2.7/site-packages/pip/wheel.py", line 479, in move_wheel_files
    maker.make_multiple(['%s = %s' % kv for kv in console.items()])
  File "/tmp/ddd/local/lib/python2.7/site-packages/pip/_vendor/distlib/scripts.py", line 364, in make_multiple
    filenames.extend(self.make(specification, options))
  File "/tmp/ddd/local/lib/python2.7/site-packages/pip/_vendor/distlib/scripts.py", line 353, in make
    self._make_script(entry, filenames, options=options)
  File "/tmp/ddd/local/lib/python2.7/site-packages/pip/_vendor/distlib/scripts.py", line 244, in _make_script
    script = self._get_script_text(entry).encode('utf-8')
  File "/tmp/ddd/local/lib/python2.7/site-packages/pip/wheel.py", line 396, in _get_script_text
    "import_name": entry.suffix.split(".")[0],
AttributeError: 'NoneType' object has no attribute 'split'

These files were included, however just to make sure.

Closes: #58