is_size_t test was reversed. Bug spotted by INADA Naoki.

test_unraisable() of test_exceptions expects that PyErr_WriteUnraisable(method)
fails on repr(method).

Before the previous change (7b8df4a5d81d), slot_tp_finalize() called
PyErr_WriteUnraisable() with a PyMethodObject. In this case, repr(method) calls
repr(self) which is BrokenRepr.__repr__() and the calls raises a new exception.

After the previous change, slot_tp_finalize() uses an unbound method: repr() is
called on a regular __del__() method which doesn't call repr(self). repr()
doesn't fail anymore.

PyErr_WriteUnraisable() doesn't call __repr__() anymore, so remove BrokenRepr
unit test.

Issue #29507: Optimize slots calling Python methods. For Python methods, get
the unbound Python function and prepend arguments with self, rather than
calling the descriptor which creates a temporary PyMethodObject.

Add a new _PyObject_FastCall_Prepend() function used to call the unbound Python
method with self. It avoids the creation of a temporary tuple to pass
positional arguments.

Avoiding temporary PyMethodObject and avoiding temporary tuple makes Python
slots up to 1.46x faster. Microbenchmark on a __getitem__() method implemented
in Python:

Median +- std dev: 121 ns +- 5 ns -> 82.8 ns +- 1.0 ns: 1.46x faster (-31%)
Co-Authored-by: INADA Naoki <songofacandy@gmail.com>

Add canonical header link on each page to corresponding major
version of the documentation.

Patch by Matthias Bussonnier.

Issue #29259, #29465: PyCFunction_Call() doesn't create anymore a redundant
tuple to pass positional arguments for METH_VARARGS.

Add a new cfunction_call() subfunction.

Serhiy Storshaka pointed me that str(path) can emit a BytesWarning: use
repr(path) instead.

Issue #29306: Destroy argstuple and kwdict if Py_EnterRecursiveCall() fails.

Write also dots into stderr, instead of stdout.

Log the OSError exception message.

* *PyCFunction_*Call*() functions now call Py_EnterRecursiveCall().
* PyObject_Call() now calls directly _PyFunction_FastCallDict() and
  PyCFunction_Call() to avoid calling Py_EnterRecursiveCall() twice per
  function call

Issue #29452: Use METH_FASTCALL calling convention for index(), insert() and
rotate() methods of collections.deque to avoid the creation a temporary tuple
to pass position arguments. Speedup on deque methods:

* d.rotate(): 1.10x faster
* d.rotate(1): 1.24x faster
* d.insert(): 1.18x faster
* d.index(): 1.24x faster

Issue #27659: use -Werror=implicit-function-declaration when possible (GCC and
Clang, but it depends on the compiler version).

Patch written by Chi Hsuan Yen.

Issue #29362: Catch a crash of a worker process as a normal failure and
continue to run next tests. It allows to get the usual test summary: single
line result (OK/FAIL), total duration, etc.