Allow several alternative names for astrosources.

[juanep97]

Sometimes there have been errors or different conventions in source names.
We should rename other_name to other_names and allow it to be a comma separated list of names.
It will allow IOP4 to work with the different conventions used along the history of -several- programs within one catalog.

E.g. 2145+067 a.k.a B 2145+067 was wrongly named B2135 in the catalog, but was observed with that name during some time due to an error in the observers spreadsheet. We could include the wrong name in the catalog (and a indication that the name is only because of an error, to reduce the files with that name).