This change moves the datetime tuple format back to the one used by all the
other ports:
(year, month, day, weekday, hour, minute, second, microsecond)
Weekday is a number between 0 and 6, with 0 assigned to Monday. It has to
be provided when setting the RTC with datetime(), but will be ignored on
entry and calculated when needed.
The weekday() method was removed, since that is now again a part of the
datetime tuple.
The now() method was updated so it continues to return a tuple that matches
CPython's datetime module.