Retrieve released Glottolog data using version tags

[xrotwang]

I just had a look at https://github.com/ropensci/lingtypology/blob/master/database_creation/glottolog_database_creation_v3.R and I think it might be more transparent - and possibly a way to support multiple versions of referenced databases - if the data was fetched using the version tag, i.e. from https://raw.githubusercontent.com/glottolog/glottolog-cldf/v4.5/cldf/codes.csv (etc) rather than from master.

[xrotwang]

Btw.: WALS also gets smallish corrections every once in a while and is at v2020.1 now, see https://github.com/cldf-datasets/wals/releases

[xrotwang]

You could also retrieve some metadata - e.g. the bibliographic citation from the CLDF metadata at https://raw.githubusercontent.com/glottolog/glottolog-cldf/v4.5/cldf/cldf-metadata.json - which might make maintenance of the package simpler over time.

[agricolamz]

Dear Robert, thank you for your comments. I've seen them long time ago, but didn't have mental sources to work...