Testing with multiple targets only uses one target language

[TaperChipmunk32]

When testing a model with multiple target languages, only one language is used for predictions. Every test file contains the same test predictions, all in one of the target languages, regardless of iso codes found in the filename.

For example, test.en.es.trg-predictions.detok.txt and test.en.fr.trg-predictions.detok.txt would both contain translations from English to French, with no Spanish translation found.