Sockeye

Changed
- Disabled dynamic batching for `Translator.translate()` by default due to increased memory usage. The default is to
fill-up batches to `Translator.max_batch_size`.
Dynamic batching can still be enabled if `fill_up_batches` is set to False.
Added
- Added parameter to force training to stop after a given number of checkpoints. Useful when forced to share limited GPU resources.

Fixed
- Fixed lexical constraints bugs that broke batching and caused large drop in BLEU.
These were introduced with sampling (1.18.64).

Changed
- The embedding size is automatically adjusted to the Transformer model size in case it is not specified on the command line.

Fixed
- Fixed type conversion in metrics file reading introduced in 1.18.79.

Fixed
- Making sure the training pickled training state contains the checkpoint decoder's BLEU score of the last checkpoint.

Fixed
- Fixed a bug introduced in 1.18.77 where blank lines in the training data resulted in failure.