+ sanity check in `in tokens` mode

fix typo

fix readme

fix: inference classifier

fix NER infer results

default `--predict_batch_size=8`

Remove deprecated fluid.memory_optimize

fix bug for regression where is_prediction ==true

fix using softmax whatever is_classify or is_regression.

fix script typo

+ missing script

Fix TypeError on ernie_encoder.py

fix command to run

Many updates

1. finetune/ pretrian fp16 amp
2. finetune/ pretrain multi processing
3. ner infer
4. py3 compat

support IO,IOB,IOE,IOBES for sequence labeling & fix en mrc

Use ==/!= to compare str, bytes, and int literals

update paper arxiv link

Identity is not the same thing as equality in Python.

$ python
```
>>> self_dtype = "float"
>>> self_dtype += "16"
>>> self_dtype == "float16"
True
>>> self_dtype is "float16"
False
```

update .run_ce.sh