ArrayDataSource __getstate__ doesn't call super

[corranwebster]

It probably should, given that AbstractDataSource.__getstate__ does things.

[rahulporuri]

note that #250 supercedes this issue and this issue can be closed if the serialization code is removed.

[corranwebster]

No, #250 does not supercede - __getstate__ is standard Python stuff (https://docs.python.org/3/library/pickle.html#object.__getstate__) and there's additional Traits support for __getstate__ IIRC.

[aaronayres35]

this was fixed in #633