util: document we want Python type mapping to be temporary I think remapping Python C API types and functions is not a great approach. I'd prefer this whole #ifdef disappeared. Add a comment so we don't forget about it.

util: define PyInt_Type on Python 3 util.h attempts to wallpaper over C API differences between Python 2 and 3. This is not the correct approach where performance is critical. But it is good enough for the current state of the Python 3 port.

parsers: return NULL from PyInit_parsers on Python 3 This function must return a PyObject* or the compiler complains.