Pytest now uses its own ``TerminalWriter`` class instead of using the one from the ``py`` library.
Plugins generally access this class through ``TerminalReporter.writer``, ``TerminalReporter.write()``
(and similar methods), or ``_pytest.config.create_terminal_writer()``.

The following breaking changes were made:

- Output (``write()`` method and others) no longer flush implicitly; the flushing behavior
  of the underlying file is respected. To flush explicitly (for example, if you
  want output to be shown before an end-of-line is printed), use ``write(flush=True)`` or
  ``terminal_writer.flush()``.
- Explicit Windows console support was removed, delegated to the colorama library.
- Support for writing ``bytes`` was removed.
- The ``reline`` method and ``chars_on_current_line`` property were removed.
- The ``stringio`` and ``encoding`` arguments was removed.
- Support for passing a callable instead of a file was removed.