0.6.1 -> 0.6.2 (facebookresearch#577)

Summary:
Changelog:
- 998ba4f: Add language models from Baevski & Auli (2018)
- 4294c4f: Add mixture of experts code from Shen et al. (2019)
- 0049349: Add example for multilingual training
- 48d9afb: Speed improvements, including fused operators from apex
- 44d27e6: Add Tensorboard support
- d17fa85: Add Adadelta optimizer
- 9e1c880: Add `FairseqEncoderModel`
- b65c579: Add `FairseqTask.inference_step` to modularize generate.py
- 2ad1178: Add back `--curriculum`
- Misc bug fixes and other features

Pull Request resolved: facebookresearch#577

Differential Revision: D14481233

Pulled By: myleott

fbshipit-source-id: 4ff8625ef1c0b24273fc65df7c5658e3c932e8b7

Add fairseq to PyPI (facebookresearch#495)

Summary:
- fairseq can now be installed via pip: `pip install fairseq`
- command-line tools are globally accessible: `fairseq-preprocess`, `fairseq-train`, `fairseq-generate`, etc.
Pull Request resolved: facebookresearch#495

Differential Revision: D14017761

Pulled By: myleott

fbshipit-source-id: 10c9f6634a3056074eac2f33324b4f1f404d4235

Online backtranslation module

Co-authored-by: liezl200 <[email protected]>

0.4.0 -> 0.5.0

Changelog:
- 97b58b4: add Transformer model from Vaswani et al. (2017)
- b2374e5: faster Transformer inference with improved caching
- 2d27ae0: simulate large mini-batch training with delayed updates (`--update-freq`)
- 7ee1d28: add FP16 training support (`--fp16`)
- 2a84f46: faster inference by removing completed sentences from the batch
- 663fd80: batched interactive generation
- 4c2ef2d: add language modeling / gated convolutional model from Dauphin et al. (2017)
- b59815b: add Hierarchical Neural Story Generation model from Fan et al. (2018)
- ff68a9e: add FairseqTask to modularize task definitions (e.g., translation, language modeling)

Merge internal changes (facebookresearch#163)