bpo-36763: Implement the PEP 587 (GH-13592)

* Add a whole new documentation page:
  "Python Initialization Configuration"
* PyWideStringList_Append() return type is now PyStatus,
  instead of int
* PyInterpreterState_New() now calls PyConfig_Clear() if
  PyConfig_InitPythonConfig() fails.
* Rename files:

  * Python/coreconfig.c => Python/initconfig.c
  * Include/cpython/coreconfig.h => Include/cpython/initconfig.h
  * Include/internal/: pycore_coreconfig.h => pycore_initconfig.h

* Rename structures

  * _PyCoreConfig => PyConfig
  * _PyPreConfig => PyPreConfig
  * _PyInitError => PyStatus
  * _PyWstrList => PyWideStringList

* Rename PyConfig fields:

  * use_module_search_paths => module_search_paths_set
  * module_search_path_env => pythonpath_env

* Rename PyStatus field: _func => func
* PyInterpreterState: rename core_config field to config
* Rename macros and functions:

  * _PyCoreConfig_SetArgv() => PyConfig_SetBytesArgv()
  * _PyCoreConfig_SetWideArgv() => PyConfig_SetArgv()
  * _PyCoreConfig_DecodeLocale() => PyConfig_SetBytesString()
  * _PyInitError_Failed() => PyStatus_Exception()
  * _Py_INIT_ERROR_TYPE_xxx enums => _PyStatus_TYPE_xxx
  * _Py_UnixMain() => Py_BytesMain()
  * _Py_ExitInitError() => Py_ExitStatusException()
  * _Py_PreInitializeFromArgs() => Py_PreInitializeFromBytesArgs()
  * _Py_PreInitializeFromWideArgs() => Py_PreInitializeFromArgs()
  * _Py_PreInitialize() => Py_PreInitialize()
  * _Py_RunMain() => Py_RunMain()
  * _Py_InitializeFromConfig() => Py_InitializeFromConfig()
  * _Py_INIT_XXX() => _PyStatus_XXX()
  * _Py_INIT_FAILED() => _PyStatus_EXCEPTION()

* Rename 'err' PyStatus variables to 'status'
* Convert RUN_CODE() macro to config_run_code() static inline function
* Remove functions:

  * _Py_InitializeFromArgs()
  * _Py_InitializeFromWideArgs()
  * _PyInterpreterState_GetCoreConfig()

1 files changed, 55 insertions, 0 deletions

diff --git a/Doc/whatsnew/3.8.rst b/Doc/whatsnew/3.8.rst
index 1180469..6102d8c 100644
--- a/Doc/whatsnew/3.8.rst
+++ b/Doc/whatsnew/3.8.rst
@@ -182,6 +182,61 @@ Would print ``x*9 + 15=42``.
 
 (Contributed by Eric V. Smith and Larry Hastings in :issue:`36817`.)
 
+PEP 587: Python Initialization Configuration
+--------------------------------------------
+
+The :pep:`587` adds a new C API to configure the Python Initialization
+providing finer control on the whole configuration and better error reporting.
+
+New structures:
+
+* :c:type:`PyConfig`
+* :c:type:`PyPreConfig`
+* :c:type:`PyStatus`
+* :c:type:`PyWideStringList`
+
+New functions:
+
+* :c:func:`PyConfig_Clear`
+* :c:func:`PyConfig_InitIsolatedConfig`
+* :c:func:`PyConfig_InitPythonConfig`
+* :c:func:`PyConfig_Read`
+* :c:func:`PyConfig_SetArgv`
+* :c:func:`PyConfig_SetBytesArgv`
+* :c:func:`PyConfig_SetBytesString`
+* :c:func:`PyConfig_SetString`
+* :c:func:`PyPreConfig_InitIsolatedConfig`
+* :c:func:`PyPreConfig_InitPythonConfig`
+* :c:func:`PyStatus_Error`
+* :c:func:`PyStatus_Exception`
+* :c:func:`PyStatus_Exit`
+* :c:func:`PyStatus_IsError`
+* :c:func:`PyStatus_IsExit`
+* :c:func:`PyStatus_NoMemory`
+* :c:func:`PyStatus_Ok`
+* :c:func:`PyWideStringList_Append`
+* :c:func:`PyWideStringList_Insert`
+* :c:func:`Py_BytesMain`
+* :c:func:`Py_ExitStatusException`
+* :c:func:`Py_InitializeFromConfig`
+* :c:func:`Py_PreInitialize`
+* :c:func:`Py_PreInitializeFromArgs`
+* :c:func:`Py_PreInitializeFromBytesArgs`
+* :c:func:`Py_RunMain`
+
+This PEP also adds ``_PyRuntimeState.preconfig`` (:c:type:`PyPreConfig` type)
+and ``PyInterpreterState.config`` (:c:type:`PyConfig` type) fields to these
+internal structures. ``PyInterpreterState.config`` becomes the new
+reference configuration, replacing global configuration variables and
+other private variables.
+
+See :ref:`Python Initialization Configuration <init-config>` for the
+documentation.
+
+See :pep:`587` for a full description.
+
+(Contributed by Victor Stinner in :issue:`36763`.)
+
 
 Other Language Changes
 ======================