uarray extend doesn't accept an iterable

[hlovatt]

The extend method of a uarray doesn't accept an iterable only a buffer. Documentations says it should be an iterable and the constructor accepts an iterable and therefore would expect extend to accept an iterable.

EG:

MicroPython v1.14-68-gd4b45898f on 2021-02-18; PYBv1.1 with STM32F405RG
Type "help()" for more information.
>>> from uarray import array
>>> a=array('b',[1,2,3])
>>> a.extend([4,5,6])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: object with buffer protocol required

[dpgeorge]

It looks like this can be added with minimal additional code by reusing the constructor code for extension.

[dpgeorge]

Fixed by 0a98f3a