* add -linear-schedule-with-warmup

* update lr scheduler usage in run_glue

* add import info

* add other 5 scheduler with warmup

* add copyright, update usage in run_glue

* simplify argument, make warmup arg support float and int

* Add some LambdaDecay scheduler with warmup, update usage in run_glue

* update classname and unify two cosine decays into one

* update usage in run_glue

* fix typo

* update WarmUp to Warmup, and update class name about Const, and update doc, and usage

* update usage of decay class

* update usage of decay class

* Add inference support for BERT.

* Update inference support for BERT.

* fix checkpoints problem.

* fix reader

* increase epoch from 100 to 200

add gpt2 model for the paddlenlp

* fix readme

* update doc

* add / for dir

* refine eval batch size

* update train

* update eval

* add the xpu support the the paddlenlp

* add the support xpu for the ernie and bert
Co-authored-by: Nwawltor <fanzeyang0904@hotmail.com>

* add transformer-xl for language model

* fix readme and change cross-entropy api

* change api back

* update lrscheduler

* minor fix

* add pre-commit