ads.py::bytes_from_dict(..) is broken for nested structures

[jimw-sics]

On line 440

                elif type(plc_datatype) is tuple:
                    bytecount = bytes_from_dict(
                        values=var[i], structure_def=plc_datatype
                    )

values=var[i] should be values=var. When var is a dict, doing getitem on the for-loop index is not meaningful, it is not a list.

Also, do not reuse variables and overwrite values, makes debugging a pain.