Update asyncio documentation

- Document the new create_task() method
- "Hide" the Task class: point to the create_task() method for interoperability
- Rewrite the documentation of the Task class
- Document the "Pending task destroyed"
- Update output in debug mode of examples in the dev section
- Replace Task() with create_task() in examples

Doc/library/asyncio-eventloop.rst

@@ -102,8 +102,8 @@ Run an event loop
 
    Run until the :class:`Future` is done.
 
-   If the argument is a :ref:`coroutine <coroutine>`, it is wrapped
-   in a :class:`Task`.
+   If the argument is a :ref:`coroutine object <coroutine>`, it is wrapped by
+   :func:`async`.
 
    Return the Future's result, or raise its exception.
 
@@ -205,6 +205,25 @@ a different clock than :func:`time.time`.
    The :func:`asyncio.sleep` function.
 
 
+Coroutines
+----------
+
+.. method:: BaseEventLoop.create_task(coro)
+
+   Schedule the execution of a :ref:`coroutine object <coroutine>`: wrap it in
+   a future. Return a :class:`Task` object.
+
+   Third-party event loops can use their own subclass of :class:`Task` for
+   interoperability. In this case, the result type is a subclass of
+   :class:`Task`.
+
+   .. seealso::
+
+      The :meth:`async` function.
+
+   .. versionadded:: 3.4.2
+
+
 Creating connections
 --------------------