SubProcess _make_inheritable

[Roland Puntaier]

SubProcess.py needs to be patched - at least in 2.4 -  to work from 
windows GUIs:

        def _make_inheritable(self, handle):
            """Return a duplicate of handle, which is inheritable"""
            if handle==None: handle=-1
            return DuplicateHandle(GetCurrentProcess(), handle,
                                   GetCurrentProcess(), 0, 1,
                                   DUPLICATE_SAME_ACCESS)