[Cython] Py_UNICODE* string support

[Nikita Nemkin]

Hi,

Please review my feature proposal to add Py_UNICODE* string support
for better Windows interoperability:
https://github.com/cython/cython/pull/191

This is motivated by my current work that involves calling lots of Windows  
APIs.

If people are interested I can elaborate on some important points, like
the choice of base type (Py_UNICODE vs wchar_t) or the nature of
Py_UNICODE* literals or why this feature is necessary at all.


Best regards,
Nikita Nemkin