[C++-sig] Boost.Python v2: iterator support

[David Abrahams]

I have just checked in support for wrapping C++ iterators as Python
iterators to the Boost.Python v2 codebase. Please see
libs/python/test/iterator.[cpp/py] for some examples. Documentation will be
forthcoming.

-Dave

+---------------------------------------------------------------+
                  David Abrahams
      C++ Booster (http://www.boost.org)               O__  ==
      Pythonista (http://www.python.org)              c/ /'_ ==
  resume: http://users.rcn.com/abrahams/resume.html  (*) \(*) ==
          email: david.abrahams at rcn.com
+---------------------------------------------------------------+