The PR description is long. See details in the PR link.

* fix eng doc, test=develop

* add import deprecated for layers, test=develop

* add block line for doc generate, test=develop

* remove todo for create_variable, test=develop

* add blank line for doc generate, test=develop

* add blank line for doc generate, test=develop

* Add multi_gru_seq_fuse_pass and tests

* fix date

* removed unused functions

* Fix en doc for rnn.py. test=document_fix

* Delete mq2007 dataset.

* polish dataloader doc detail, test=decument_fix

* fix commnet error

* fix word error

* test=develop, optimize global_step

* refine doc of bernoulli

* fix some problems

* fix unsqueeze

* fix squeeze

* fix doc

* update, test=develop

* fix English doc for dice_loss, log_loss, unfold and NLLLoss API test=document_fix

* add early stopping

* add doc for early stopping

* fix sample code bugs

* update infer of mode, update doc, add unittests to increase coverage rate

* fix sample code for early stopping

* update sample code and unittests

* reduce time cost of test_callbacks unittest

* fix model.py code style error

* update hapi save_inference_model output pathname

* update hapi save_inference_model output pathname

* use new 2.0-api paddle.static.io.load_inference_model

* add unittests to increase coverage rate

* ps gpu transpile

* ps gpu

* remove op

* gps trainer

* local ps

* add macro

* HeterBox

* def cuda

* tab

* code style

* style

Co-authored-by: Thunderbrook <a754913769#163.com>

* refactor momentum op to combine weight_decay (scale op and sum op)

* add musl docker build script

* rm space test=document_fix

* fix some docs and types errors test=document_fix

* move install of python requirement to docker build

* add copyright to docker file.

* add extr opts

* format docs

fix error for Can not find test to add properties to:test_parallel_dygraph_transformer,test_parallel_dygraph_sparse_embedding (#28968)

* change avg pooling and global pooling to trt layer

* add support for static shape global pooling

* modify trt errmsg

* optimize conv performance

* add lr scheduler

* fix conv_transpose unittest. test=develop

* fix dataloader. test=develop

* fix param base trainable set failed

* add unittest

* fix typo

* polish comment

Adding uint8 support for squeeze operator.

* test=develop, bug fix for embeddings padding

* fix raise Value for Embedding

Change-Id: I6d343fceee369a5796ad59cca5c91fdd15429125
Co-authored-by: NseiriosPlus <tangwei12@baidu.com>

* fix code example, test=document_fix