[Developers] language codes

[Arthur van Hoff]

Hi Kurt,

> We'll get to that ASAP, but in the meantime, you can download
> 
> http://www.ethnologue.com/14/iso639/all_639-1.tab
> 
> to map 639-1 to 639-3 codes for lookup with MQL.

I tried that mapping, but I don't think that file maps 639-1 to 639-3
correctly. The 3 letter codes appear to be SIL codes (not sure what
these are), and the mapping is ambiguous (some 2 letter codes map to
many 3 letter codes).

I'll special case English for now, and move on, but I would appreciated
it if someone could take a look at this and fix up the various language
codes to be correct.

Thanks.