Should work even with different python versions on client and server.

This fixes the following error:

    "import_name": entry.suffix.split(".")[0],
    AttributeError: 'NoneType' object has no attribute 'split'

See
https://pythonhosted.org/setuptools/setuptools.html#automatic-script-creation

This should solve the TypeError reported in #53 and some others I found
while testing the fix.

Closes: #53

The PF firewall that is included in the FreeBSD base system does not
have exactly the same data structures as the OSX version. This commit
fixes the offsets and some field types that are also different. Tested
with FreeBSD 10.2 and OSX 10.11.2.

Closes: #49.

Closes: #48

The removal loop should probably be outside the iteration loop.

Also support multiline debug output better.

* setup_firewall sets the firewall up.
* restore_firewall restores the firewall to initial state.

When executing with the option --syslog start redirecting to
syslog immediately after the command line options are validated.
This way when using with some init daemon, e.g., upstart all the
relevant information (connection failures, etc) can be retrieved from
the log instead of being lost to stdout or stderr.

Closes: #40

This is no longer used by modern MacOSX and not getting tested.

It also required a do_wait() function which was a complication for
sshuttle as a whole.

Can get resurrected if required.

Closes: #36.