-------------------
* add `bitarray.util.serialize()` and `bitarray.util.deserialize()`
* allow whitespace (ignore space and `\n\r\t\v`) in input strings,
e.g. `bitarray('01 11')` or `a += '10 00'`
* add `bitarray.util.pprint()`
* When initializing a bitarray from another with different bit-endianness,
e.g. `a = bitarray('110', 'little')` and `b = bitarray(a, 'big')`,
the buffer used to be simply copied, with consequence that `a == b` would
result in `False`. This is fixed now, that is `a == b` will always
evaluate to `True`.
* add test for loading existing pickle file (created using bitarray 1.5.0)
* add example showing how to [jsonize bitarrays](../examples/extend_json.py)
* add tests