huggingface/transformers: Longformer

• Longformer (@ibeltagy)
• Longformer for QA (@patil-suraj + @patrickvonplaten)
• Longformer fast tokenizer (@patil-suraj)
• Longformer for sequence classification (@patil-suraj)
• Longformer for token classification (@patil-suraj)
• Longformer for Multiple Choice (@patrickvonplaten)
• More user-friendly handling of global attention mask vs local attention mask (@patrickvonplaten)
• Fix longformer attention mask type casting when using APEX (@peskotivesgeroff)

• Long Sequence Modeling with Reformer (@patrickvonplaten)
• Fine-tune BART for summarization (@ohmeow)
• Fine-tune a pre-trained Transformer on anyone's tweets (@borisdayma, @lavanyashukla)
• A step-by-step guide to tracking hugging face model performance with wandb (@jxmorris12, @lavanyashukla)
• Fine-tune Longformer for QA (@patil-suraj)
• Pretrain Longformer (@ibeltagy)
• Fine-tune T5 for sentiment span extraction (@enzoampil)

Archive maps were dictionaries linking pre-trained models to their S3 URLs. Since the arrival of the model hub, these have become obsolete.

This PR is breaking for the following models:

"cl-tohoku/bert-base-japanese" "cl-tohoku/bert-base-japanese-whole-word-masking" "cl-tohoku/bert-base-japanese-char" "cl-tohoku/bert-base-japanese-char-whole-word-masking" "TurkuNLP/bert-base-finnish-cased-v1" "TurkuNLP/bert-base-finnish-uncased-v1" "wietsedv/bert-base-dutch-cased" "flaubert/flaubert_small_cased" "flaubert/flaubert_base_uncased" "flaubert/flaubert_base_cased" "flaubert/flaubert_large_cased"

all variants of "facebook/bart"

• Fix convert_token_type_ids_from_sequences for fast tokenizers (@n1t0, #4503)
• Fixed the default tokenizer of the summarization pipeline (@sshleifer, #4506)
• The max_len attribute is now more robust, and warns the user about deprecation (@mfuntowicz, #4528)
• Added type hints to modeling_utils.py (@bglearning, #3911)
• MMBT model now has nn.Module as a superclass (@shoarora, #4533)
• Fixing tokenization of extra_id symbols in the T5 tokenizer (@mansimov, #4353)
• Slow GPU tests run daily (@julien-c, #4465)
• Removed PyTorch artifacts in TensorFlow XLNet implementation (@ZhuBaohe, #4410)
• Fixed the T5 Cross Attention Position Bias (@ZhuBaohe, #4499)
• The transformers-cli is now cross-platform (@BramVanroy, #4131) + (@patrickvonplaten, #4614)
• GPT-2, CTRL: Accept input_ids and past of variable length (@patrickvonplaten, #4581)
• Added back --do_lower_case to SQuAD examples.
• Correct framework test requirement for language generation tests (@sshleifer, #4616)
• Fix add_special_tokens on fast tokenizers (@n1t0, #4531)
• MNLI & SST-2 bugs were fixed (@stdcoutzyx, #4546)
• Fixed BERT example for NSP and multiple choice (@siboehm, #3953)
• Encoder/decoder fix initialization and save/load bug (@patrickvonplaten, #4680)
• Fix onnx export input names order (@RensDimmendaal, #4641)
• Configuration: ensure that id2label always takes precedence over num_labels (@julien-c, direct commit to master)
• Make docstring match argument (@sgugger, #4711)
• Specify PyTorch versions for examples (@LysandreJik, #4710)
• Override get_vocab for fast tokenizers (@mfuntowicz, #4717)
• Tokenizer should not add special tokens for text generation (@patrickvonplaten, #4686)