[RFE] Fall back to matching two-letter language code

[Marcel Waldvogel]

Problems:

1. My system language is de_CH, but only de_DE is listed among the supported languages. So it falls back to using the English version instead of the closer de_DE. (Yes, de_CH could be added to the list of supported languages, but also see the next item)
2. Some languages have a long list of country codes. E.g. Spanish has some 18 countries listed (and the list probably still is not complete)

Proposal:

1. Do the current 5-character match (language+country)
2. If there is no 5-character match, try with a two-character match (language)
3. If there is no two-character match either, fall back to the default language

This would result in a more appropriate language being chosen.