Uniformize argument names of "call" functions

Issue #28838: Rename parameters of the "calls" functions of the Python C API.

* Rename 'callable_object' and 'func' to 'callable': any Python callable object
  is accepted, not only Python functions
* Rename 'method' and 'nameid' to 'name' (method name)
* Rename 'o' to 'obj'
* Move, fix and update documentation of PyObject_CallXXX() functions
  in abstract.h
* Update also the documentaton of the C API (update parameter names)

Include/ceval.h

@@ -8,16 +8,18 @@ extern "C" {
 /* Interface to random parts in ceval.c */
 
 PyAPI_FUNC(PyObject *) PyEval_CallObjectWithKeywords(
-    PyObject *func, PyObject *args, PyObject *kwargs);
+    PyObject *callable,
+    PyObject *args,
+    PyObject *kwargs);
 
 /* Inline this */
-#define PyEval_CallObject(func,arg) \
-    PyEval_CallObjectWithKeywords(func, arg, (PyObject *)NULL)
+#define PyEval_CallObject(callable, arg) \
+    PyEval_CallObjectWithKeywords(callable, arg, (PyObject *)NULL)
 
-PyAPI_FUNC(PyObject *) PyEval_CallFunction(PyObject *obj,
+PyAPI_FUNC(PyObject *) PyEval_CallFunction(PyObject *callable,
                                            const char *format, ...);
 PyAPI_FUNC(PyObject *) PyEval_CallMethod(PyObject *obj,
-                                         const char *methodname,
+                                         const char *name,
                                          const char *format, ...);
 
 #ifndef Py_LIMITED_API