Language with (non ref) fallback language
Ability to define 'variances' of a language.
fr_FR would give
module.key.1: "1 translation"
module.key.2: "2 translation"
and fr_BE would give
module.key.2: "2 other translation"
still, when user is in fr_BE, he should get "1 translation" for module.key.1
by configuring fr_FR as fallback language for fr_BE