* update to paddle 2.

* update readme

* upgrade multi card fintune example

* use paddle.AdamW, use grad acc

* bump propeller

* remove grad acc

* fix ner

* update propeller & distribued sample

* wip

* +seq2seq

* format

* fix erneigen

* fix pretrain

* fix static

* update propeller  for py37 compat

* fix pretrain static

* up readme

* update readme

* static pretrain

* remove optimization out of core libray

* ner use `cross_entropy`, use `ignore index`

* fix dygraph pretrain: add stop criteria

* bugfix, LN wrong initialize

* add grad acc for classifiction task

* seq2seq use fp32 when decoding

* use `paddle.io.DataLoader`

* + distill

* update readme

* update distill fig link

* propeller use vdl

* do not use pure fp16 for static graph
Co-authored-by: Nchenxuyi <work@yq01-qianmo-com-255-129-11.yq01.baidu.com>

Co-authored-by: Nsuweiyue <suweiyue@baidu.com>

* use pathib, fix #546

* use encoding

* Update feature_column.py

fix #559

* upgrade to the new lac interface

* remove jieba

* + init_checkppoint for seq_cls demo

* backto jieba

* fix pretrain reader  encoding

* dygraph

* update bce

* fix readme

* update readme

* fix readme

* remove debug log

* remove chn example

* fix pretrain

* tokenizer can escape special token
rename mlm_bias

* update readme

* 1. MRC tasks
2. optimize truncate strategy in tokenzier
3. rename `ernie.cls_fc` to `ernie.classifyer`
4. reorg pretrain dir

* + doc string

* update readme

* Update README.md

* Update README.md

* Update README.md

* update pretrain

* Update README.md

* show gif

* update readme

* fix gif; disable save_dygrpah

* bugfix

* + save inf model
+ inference
+ distill
+ readme

* Update README.md

* + propeller server

* Update README.md

* Update README.md

* Update README.md

* + sementic analysis(another text classification)

* transformer + cache
fix tokenization bug

* update reamde; fix tokenization

* Update README.md

* Update README.md

* Add files via upload

* Update README.md

* Update README.md

* Update README.md

* infer senti analysis

* + readme header

* transformer cache has gradients

* + seq2seq

* +experimental

* reorg

* update readme

* Update README.md

* seq2seq

* + cnndm evluation scripts

* update README.md

* +zh readme

* + publish ernie gen model

* update README.md

* Update README.zh.md

* Update README.md

* Update README.zh.md

* Update README.md

* Update README.zh.md

* Update README.md

* Update README.zh.md

* Update README.md

* Update README.zh.md

* Update README.zh.md

* Add files via upload

* Update README.md

* Update README.zh.md

* Add files via upload

* release ernie-gen (#444)

* release ernie-gen

* add .meta

* del tag

* fix tag

* Add files via upload

* Update README.zh.md

* Update README.md

* Update and rename README.zh.md to README.eng.md

* Update README.eng.md

* Update README.md

* Update README.eng.md

* Update README.md

* Update README.eng.md

* Update README.md

* Update README.md

* Update README.md

* Update README.eng.md

* Update README.eng.md

* Update README.eng.md

* Update README.md

* Update README.md

* Update README.md

* Update README.md
Co-authored-by: Nkirayummy <shi.k.feng@gmail.com>
Co-authored-by: Nzhanghan <zhanghan17@baidu.com>