machine-translation

It would be cool to add Google Translate support, because most likely Google Translate is better than Microsoft Translate.

And maybe it would be good idea to use Google Apps Script, because it has a free unlimited Google Translate. Here is an [example article](https://techstreams.github.io/2016/01/07/translation-automation-with-wor

Hi, I am so interesting in your project, and wonder if you need contributor and how could I make my own contribution?

We may want to start using the CTranslate2 repetition_penalty (new in 2.7) to reduce constantly repeating the same word.

setting pretrained_model_name will not only define the model arch but also load the pre-trained checkpoint. We should have another hparam to control whether to load pre-trained checkpoint or not.