Check for currency support

[MrBrezina]

As mentioned in #60

Currencies are probably best handled by an independent check as they, imho, should be mapped to countries/states rather than languages.

[alerque]

Are currency symbols part of the CLDR data set?

[MrBrezina]

@alerque I am not sure. We have some basic currencies now and the structure allows for inclusion currency language per language. Not ideal (currencies are related to countries rather than languages), but they are treated as auxiliary in terms of detections, i.e. they are suggestions.