* add paddle.fleet.AsyncOptimizer
Co-authored-by: Ndongdaxiang <dongdaxiang@baidu.com>

* add pin memory control

* fix buffered reader init problem

* fix unittest error

* add unittest for coverage

* add cuda pinned place branch

* add unittest

* add skip when not gpu

* support multi-ps training mode for fleetrun; test=develop

1. update document template for unary elementwise layers(a.k.a. activation layer);
2. remove generate_op_noattr and use generate_activation instead; remove redundant function copies;
3. minor update for docstring to fix rst format errors.
4. fix doc for Rsqrt OP
5. add sample code for each activation separately;
6. remove the unused deprecated decorator.

* Change use_quantizer attribute name and data type

* Fix problem with setting attribute

* Add changes due to review

* Small change in function

* Restore use_quantizer attr for compatibility

* enable check_dygraph for mkldnn activation tests

* TestMKLDNNSwishDim4 float32->self.dtype

* refine unsqueeze, test=develop

* update unsqueeze, test=develop

* refine unsqueeze, test=develop

* refine unsqueeze, test=develop

* update

* remove None, test=develop

* follow comments

* support bool

* update doc

* follow comments

* merge develop

[Dy2Stat-ErrorMessage]Optimize error value to improve readability when error raised in runtime.  (#25970)

* don't remove op_callstack

* [Dy2Stat-ErrorMessage] Optimize error value to improve readability if error raised in run-time. 
  1. update op_callstack with original information;
  2. simplify error value to improve readability if error raised in run-time.

* Fix error in Python3. 

* fix large scale KV 
* fix single training using async ssa graph

* add flags_call_stack_level

* update

* refine code

test=develop

* add limit support for load_dygraph loading jit.save result

* simplify unittest

* add unittests for coverage

* remove encoding limit of loading extra var info

* [Dy2Stat-ErrorMessage]Enhance original error and create new exception. test=develop

* Delete redundant code and change func name to create_and_update_origin_info_map. 

* optimize loop_transformer. 

* fix bug in print_transformer.

* Modify code according to the comments.

* remove global variable

* refine code

* fix trt plugin registry without trt lib

* support trt4

* refine code style

* test=develop,test=document_fix, remove the out args

* fleet_util move to paddle.fleet
Co-authored-by: NWuHaobo <wuhaobo1994@gmail.com>
Co-authored-by: Ntangwei12 <tangwei12@baidu.com>

* refine stack in dygraph mode, test=develop

* update stack, test=develop

* rename Variable to Tensor, test=develop

* add name args to fluid.layers.stack, test=develop

* follow comments

* update doc

* update doc

* follow comments

* move dataset to fleet
test=develop

* fix
test=develop

* fix
test=develop

* fix
test=develop

* test=develop

* test=develop

* test=develop

* test=develop

* test=develop

* test=develop

* test=develop

* Add oneDNN fusion_gru kernel and fix fc+gru pass
test=develop

* Formatting changes
test=develop

* Lint fixes
test=develop

* Add memory::format_tag::any to GRU weights
test=develop

* Fix build with CUDA

* Fix build with CUDA v2

* add heter ps mode

* code style
test=develop

* add with_pslib
test=develop

* unitest
test=develop

* code style
test=develop

* code style
test=develop

* code style
test=develop

* code style
test=develop

* code style
test=develop

* code style
test=develop

* code style
test=develop

* code style
test=develop

* test monitor
test=develop

* prepare trainer
test=develop

* code style
test=develop

* add paddle.utils.deprecated.

* add docstring. test=develop

* add alias paddle.utils.deprecated. test=develop

* rm deprecated in python/paddle/fluid/annotations.py. test=develop

* 1. check version before warning. 2. bug fix. test=develop

* bug fix. test=develop

* use paddle.fluid.require_version. test=develop

* fix doc

* fix doc. test=develop

* fix doc. test=develop

* bug fix. test=develop

* use packaging.version. test=develop.

* enhance doc. test=develop

* add compare_version function. test=develop

* add version.py. test=develop

* remove packaging. test=develop

* move compare_version to deprecated.py. test=develop

* remove print. test=develop

* fix. test=develop

* fix. test=develop

* fix. test=develop

* fix. test=develop

* inline. test=develop

* fix. test=develop

* add uncombined_weight_to_state_dict API

update the sort api, delete unused ouput index tensor

fix invalid read of pnorm gradient function and delete the unused code

Add dgc to fleet meta optimizer, rm dgc from optimizer all

* generate context during compile

* cunn8 support
test=develop

* fix ci error
test=develop

test=develop

* Add some error messages for the op without double grads.

* fix the test_imperative_double_grad UT.

* add apply for Layer

* add fleetrun command for distributed running; test=develop