py/objtextio: Add .flush() and .close() methods.
py/objtextio: Add .flush() and .close() methods.

These get actually called in the real-world code, so we need to provide them
(by dispatching to the underlying stream of course). These are implemented
as Python-level methods, not C-level ->ioctl() vmethod, to emphasize that
text streams are generally not suitable for direct usage where bytes-level
behavior (e.g. sizes in bytes) are expected.

These are also currently provided unconditionally, config options can be
added later.

Change-Id: I354443471140e92f91b6c0d8c93cf22444eb40a6
Signed-off-by: Paul Sokolovsky <9dc5061f178bb11813e14f1ed02ba27eaf21fa5d@users.sourceforge.net>

pfalcon/micropython,pfalcon/micropython,pfalcon/micropython,pfalcon/micropython,pfalcon/micropython