Add languages to cards
Convert dictionaries to refer to real language objects
Fix language detection to return a real language object

I'm trying to stop passing around ISO 639-1 codes everywhere.  This
should be pretty much the last.
Also ensure that we don't return languages for the empty string

Just thought I'd check this.
Auto-detect language in GUI

This was an unusually tricky patch to get working.  Not sure why.
Still lots of work left to do before it's usable.
Automatically select dictionaries for the chosen language
Sort dictionaries by quality score
Keep dictionary choice stable even when no dictionary is available
Save chosen language to database
Use reasonable deck names for each language
Enforce languages on reviewed cards
Improve CSS for language selector
Update language immediately after paste
Fix dictionary seed creation
Fix null keys in seeds