* Fixed indexing temps for non-python objects.
* Moved cleanup into release_temps since the temps survived into the result_code.

* Fixed indexing temps for non-python objects.
* Release another temp in PyMethodCallNode.
  Was causing warnings in generators_py.
* Moved cleanup into release_temps since the temps survived into the result_code.

* Prevent fused dispatcher optional arguments being overwritten

If the 5th argument of the regular functions was optional it'd
overwrite the _fused_sigindex default of the dispatcher, causing
type errors at runtime.

closes https://github.com/cython/cython/issues/3511

Closes https://github.com/cython/cython/issues/3430

Closes https://github.com/cython/cython/issues/3430

This allows things to work like:
    # in pxd file
    from libc.math cimport sin

    # in py file
    if not cython.compiled:
        from math import sin  # previously failed with cython compile
           # error because it was assigning to a cdef name

This seems worthwhile because it makes it easier to write code
that re-assigns cdef names and so works in both modes.

Prevent calling PyObject_GC_Track() in __Pyx_CyFunction_New() when instantiating a fused function before the object fields of the fused function subtype are fully initialised.
See https://bugs.python.org/issue38392
Closes GH-3215.
Supersedes GH-3216.

Sprinkle lots of branch prediction hints in places where exceptions are being handled or otherwise exceptional cases occur.

Mainly helps for adding attributes to classes, but undoubtedly fixes other things too.

* Add is_partitioned and partition to libcpp.algorithm
* Add is_sorted and is_sorted_until to libcpp.algorithm
* Add partition_copy, stable_partition, and partition_point to libcpp.algorithm
* Move tests for sort and partial_sort into cpp_stl_algo_sorting_ops, add greater to libcpp.functional
* Add partial_sort_copy to libcpp.algorithm
* Add stable_sort to libcpp.algorithm
* Add nth_element to libcpp.algorithm
* Add missing except specifiers in libcpp.algorithm