Here is the long promised bytes iterator view. It was much, *much*
easier to write it than I have thought. In fact I spent more time fixing
the indention than to modify the code from striterator.

I haven't written an unit test for it. The other iterators don't have
extra tests, too.

>>> iter(bytes(b"abc"))
<bytesiterator object at 0xb7cc578c>
>>> for i in iter(bytes(b"abc")): print(i)
...
97
98
99
>>> for i in bytes(b"abc"): print(i)
...
97
98
99