Updated LOSC API to handle multiple tags and versions
This PR updates the LOSC API to handle multiple dataset tags and versions. This solves the problem of separating uncleaned 'C00'
data from cleaned 'CLN' data, and also multiple versions of the same data. By default the highest discovered version is returned, while multiple tags raises a
ValueError` that lists the available tags.
TimeSeries.fetch_open_data
documentation was updated to describe the new kwargs, and give examples of how to use them.