fix ASCII compatibility check in __Pyx_init_sys_getdefaultencoding_params(): strncmp() stops at first NUL byte which is the first byte in this case (i.e. no comparison is done at all)

IPython magics

make encoding setup code safer by not expecting sys.getdefaultencoding() to safely return a bytes object

avoid C compiler warnings for different integer types and signedness when bounds-checking index in obj.pop() optimisation

Expanded POSIX interface

This reverts commit dab5ac36.

Fix typos in the CPython module include file