Municipality acronyms: 1st / 2nd language

[barthanssens]

The labels "first" and "second" language don't mean anything in Brussels (both NL and FR are considered equal), and makes it more complicated to process in applications that want to display a label in the language of the user (regardless of the language is "1st" or "2nd").

Suggestion is to just label the names according to language tag, since the "first" and "second" label (if available / meaningful) can be derived from the language regime property