BLEU on a scale of 0 to 100

[pmichel31415]

I can't think of any good reason to have BLEU on the 0 to 1 scale. Instead of making the code more complicated by adding an option, I propose we make 0-100 BLEU the default.

[neubig]

Thanks. I think we should at least

1. be consistent across the various evaluation metrics, such as BLEU, chrF, and METEOR
2. maybe have a "score_scale" variable somewhere, even if it's a pre-defined constant. That way if we (or a user) want to change it later we can

[pmichel31415]

OK I extended this to BLEU, chrF, WER and METEOR. I am less familiar with the other scorers so I don't know the standard, let me know if I should extend to RIBES, ROUGE and the length ratio.

This also adds a --scorer_scale option

[neubig]

Thanks! I think RIBES and ROUGE should also be scaled. Length ratio maybe not?

[pmichel31415]

Should be done (and bug free) now