Added interface to LOSC Timeline segments
This PR adds a new method DataQualityFlag.fetch_open_data
to retrieve Timeline segments from LOSC, and a new example that uses this method to generate a multi-segment spectrogram of open data.
This PR adds a new method DataQualityFlag.fetch_open_data
to retrieve Timeline segments from LOSC, and a new example that uses this method to generate a multi-segment spectrogram of open data.