Brought in enough of the posixmodule.c code to support path conversion
Compiles under 2.x & 3.x
Windows version running under 2.x & 3.x
Just-about working first pass at common iterator code
No need to incref the iterator; we own it and we'll PyObject_Del it in the dealloc slot
Sketch out a posix version of the iterator
Fixed up compilation on Posix