Reading a wfdb record has excessive lead selection

[Skorik99]

ecglib.data.dataset.EcgDataset.read_ecg_record method takes leads argument to slice ecg_record when open it with wfdb type. But this slice is excessive because when creating an instance of EcgRecord class it happens again:

full_ecg_record_info = EcgRecord(
            signal=ecg_record[self.leads, :],
            ...
        )

So, the creating an EcgDataset with wfdb signal and custom sequence of leads (for example [0, 5, 6, 7, 8, 9, 10, 11]) it raised an error.