Sockeye

Added

- Added scripts for processing Sockeye benchmark output (`--output-type benchmark`):
- [benchmark_to_output.py](sockeye_contrib/benchmark/benchmark_to_output.py) extracts translations
- [benchmark_to_percentiles.py](sockeye_contrib/benchmark/benchmark_to_percentiles.py) computes percentiles

Fixed

- Fix problem identified in issue 925 that caused learning rate
warmup to fail in some instances when doing continued training

Changed

- Use dataclass module to simplify Config classes. No functional change.

Fixed

- Fixes the problem identified in issue 890, where the lr_scheduler
does not behave as expected when continuing training. The problem is
that the lr_scheduler is kept as part of the optimizer, but the
optimizer is not saved when saving state. Therefore, every time
training is restarted, a new lr_scheduler is created with initial
parameter settings. Fix by saving and restoring the lr_scheduling
separately.

Fixed

- Fixed issue with LearningRateSchedulerPlateauReduce.__repr__ printing
out num_not_improved instead of reduce_num_not_improved.

Fixed

- Fixed issue with dtype mismatch in beam search when translating with `--dtype float16`.