Convert macros to static inline functions to avoid macro pitfalls,
like duplication of side effects:
* DK_ENTRIES()
* DK_UNICODE_ENTRIES()
* PyCode_GetNumFree()
* PyFloat_AS_DOUBLE()
* PyInstanceMethod_GET_FUNCTION()
* PyMemoryView_GET_BASE()
* PyMemoryView_GET_BUFFER()
* PyMethod_GET_FUNCTION()
* PyMethod_GET_SELF()
* PySet_GET_SIZE()
* _PyHeapType_GET_MEMBERS()
Changes:
* PyCode_GetNumFree() casts PyCode_GetNumFree.co_nfreevars from int
to Py_ssize_t to be future proof, and because Py_ssize_t is
commonly used in the C API.
* PyCode_GetNumFree() doesn't cast its argument: the replaced macro
already required the exact type PyCodeObject*.
* Add assertions in some functions using "CAST" macros to check
the arguments type when Python is built with assertions
(debug build).
* Remove an outdated comment in unicodeobject.h.
Add new functions to pack and unpack C double (serialize and
deserialize):
* PyFloat_Pack2(), PyFloat_Pack4(), PyFloat_Pack8()
* PyFloat_Unpack2(), PyFloat_Unpack4(), PyFloat_Unpack8()
Document these functions and add unit tests.
Rename private functions and move them from the internal C API
to the public C API:
* _PyFloat_Pack2() => PyFloat_Pack2()
* _PyFloat_Pack4() => PyFloat_Pack4()
* _PyFloat_Pack8() => PyFloat_Pack8()
* _PyFloat_Unpack2() => PyFloat_Unpack2()
* _PyFloat_Unpack4() => PyFloat_Unpack4()
* _PyFloat_Unpack8() => PyFloat_Unpack8()
Replace the "unsigned char*" type with "char*" which is more common
and easy to use.
