* Add linear learning warmup method

This warmup lr can be combinated with other learning rate strategies.
For example:
            decayed_lr = fluid.layers.linear_lr_warmup(
                fluid.layers.piecewise_decay(boundaries, lr_steps),
                warmup_steps, start_lr, end_lr)

* fix cudnn batch norm accuracy test=develop

* fix cudnn batch norm accuracy test=develop

* disable failed test for later fix test=develop

* fix compiled
test=develop

* follow comments test=develop

* Add DecoupledWeightDecay

* fix comments of 16410, test=develop

* modify inplace_op_inference_test according to pass interface change, test=develop

test=develop

test=develop

test=develop

* fuse optimizer

* Revert "[MKL-DNN] Fix to crash of Transformer when mkldnn is to be used (#16233)"

This reverts commit 13816dd4.
Apart from enabling transformer for MKL-DNN

* Revert "- MKL-DNN pooling updated to set_prim_desc"

This reverts commit c63f6b20.

Conflicts:
	paddle/fluid/operators/mkldnn/concat_mkldnn_op.cc

* Revert "[MKL-DNN] MKL-DNN specific Tensor modification (#15429)"

test=develop

This reverts commit dec9cf53.

* - concat compilation fix

- lint

test=develop

- Lint fixes

test=develop

- Lint fixes

test=develop

- Fix Transpose MKLDNN op

test=develop

* fix threaded executor bug
test=develop

* change the order of class member
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* Fix Travis CI
test=develop

refine trt first run
add quant dequant fuse pass
omit simplify_anakin_priorbox_detection template
omit transpose_flatten_concat_fuse template
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test=develop

test=develop

test=develop

* modify the interface of Pass::Allay
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* Polish code
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* Fix Travis CI
test=develop

* fix Pass::Apply interface
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* Fix Travis CI
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test=develop

test=develop

add include headers to fix travis-ci
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test=develop

* Refine default MKL-DNN Pass order

test=develop

* Add comment to default MKL-DNN Pass list

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* C-API quantization core

test=develop
Co-authored-by: NSylwester Fraczek <sylwester.fraczek@intel.com>

* Decouple Quantizer from AnalysisPredictor

test=develop

* fixes after review

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* renamed mkldnn quantize stuff

test=develop

* remove ifdef from header file

test=develop

* test=develop, fix space_to_depth_doc

* test=develop, refine indent

* test=develop, refine code

* test=develop, add api spec

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test=develop

test=develop

* Disable compare for accuracy issue.

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* Add todo comments to show more information.

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* test=develop, add install check

* test=develop, add install check scripts

* test=develop, refine language

* test=develop, add api spec

* test=develop, change cdn to bj to pass ci

* extend the slice function for python
test=develop

* test=develop, add some Layers and tests

* test=develop, add more layers

* test=develop, add more layers

* test=develop, add force cpu option

* Update test_layers.py

remove pdb

* test=develop, refine code

* fix cdn issue, test=develop

* fix memory optimize bugs, test=develop

* fix memory optimize bugs, test=develop

* remove add/sub_2 op, test=develop

* disable memory_optimize by default, test=develop

* disable inplace activation in python, test=develop

* fix unittests, test=develop

* fix unittests, test=develop

* bug-fix, test=develop

test=develop

* update jitkernel doc

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* follow comments

* follow comments

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test=develop