This commit was manufactured by cvs2svn to create branch
'null_ptr_is_none'.

svn path=/branches/null_ptr_is_none/boost/boost/python/; revision=8443
Began trying to get 0 pointers to be translated to/from None

svn path=/branches/null_ptr_is_none/boost/boost/python/; revision=9374
Removed old branches.

svn path=/branches/null_ptr_is_none/boost/boost/python/; revision=38550