2.more 'pythonic' module tree
3.moved datasource init into __init__.py
(no more 'ugly' setdlflags) - needs testing
4.datasources dir is now set by the build process (require 2.4)
5.methods (e.g __repr__) can be 'injected' from python (see mapnik/__init__.py)
2.to_string method in Envelope
3.filter_factory - static method
4.mapnik_envelope.cpp - more bindings
TODO - fix __str__ , .def(str(self)) - doesn't compile at the moment