Port to Python 3

Made some changes to allow compilation with python 3.

One commit is for pyglue itself and consists of
-A bit of code changes but not much
-Macros in PyUtil.h
-Some ifdef code but not much neither

The other commit is to allow building the doc with python 3
it is basically an update of the python dependencies (distribute, docutils, sphinx and the sphinx patch)

Test with python 2.5, 2.6 and 3.3

Xavier