Add Pipeline Concurrency Train Mode:
- Cpp: pipeline_trainer & section_worker
- Python: PipelineOptimizer
- Add a new data_feed type: PrivateInstantDataFeed
- Add a test demo of pipeline trainer and the test model is gnn
- Do not support win32 now

* remove attribute in Allocator::Allocate, test=develop

* fix travis ci error, test=develop

* fix cuda/cudnn version detection error, test=develop

* fix again, test=develop

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* revise conv layer cudnn algo choose test=develop

* update for code style test=develop

* update for code style test=develop

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* add __str__ method for tensor and lodtensor to support print test=develop

*  Enable assign operator for a ngraph, test=develop

* Cross_entropy operators needs to be updated

* Revert "Revert "Fix allocator bug""

This reverts commit 174d0d0b.

* Revert "fix travis ci"

This reverts commit 5656fa9f.

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* add inlined_vector.h, test=develop

* add inlined_vector_test,test=develop

* Relu6 is the bottleneck op for Mobilenet-v2. As the mkldnn supports the conv/relu6 fusion, we implement it fusion via cpass way. Due to the int8 enabling for this fusion will be supported in MKLDNN v0.20, so this PR is focused on the fp32 optimization.

Below table shows the benchmark(FPS) which measured on skx-8180(28 cores)
Batch size | with fusion | without fusion
-- | -- | --
1 | 214.7 | 53.4
50 | 1219.727 | 137.280

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* Fix the format issue

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* Add the missing nolint comments.

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* Fix the typos.

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* Register the conv_brelu_mkldnn_fuse_pass for the MKLDNN engine.

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* Adjust the indentation.

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* Add the test_conv_brelu_mkldnn_fuse_pass case.

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* Slightly update the code per Baidu comments.
Let the parameter definition embedded into the code.
That's will make the code easy to understand.

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* Add conv2d_grad_grad_op
* Extracte the cuDNN conv algo searching code in conv_cudnn_helper.h.
    - Now use it in conv2d_grad_grad.
    - Will simply the searching code in conv2d and conv2d_grad in next PR.
* Enhance and fix bug in unit testing of gradient_checker.
* Support to fetch empty variables，return None in Python.

* Refine elementwise kernel.

Add a simple cuda kernel if grad x and y both exist
Use 2D block cuda kernel to do broadcast.

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Signed-off-by: Nzhaoyuchen <zhaoyuchen01@baidu.com>

* refine code.

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Signed-off-by: Nzhaoyuchen <zhaoyuchen01@baidu.com>

* refine code.

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Signed-off-by: Nzhaoyuchen <zhaoyuchen01@baidu.com>

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* added lrn op test=develop

* Added CreateConstant method test=develop

* avoid duplicates test=develop

* remove unused FLAGS_warpctc_dir

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* remove FLAGS_warpctc_dir

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1. Use CudnnWorkspaceHandle in exhaustive search of conv_cudnn.
2. For Ops using CudnnWorkspaceHandle in exhaustive search, release their GPU memory after exhaustive search.

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* make_conv_cudnn_ws_size_configurable, test=develop

* change std::max to std::min
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* speedup gc and inplace softmax_with_cross_entropy_grad
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* refine models gpu mem
Merge skip vars and warning messages of mem opt
remove relu mem opt
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* follow comments
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* - Reuse of conv PD

- conv transpose pd reused

- Added PD reusing of softmax and Batch Norm

- Refactoring and removal of not needed routines of mkl-dnn ops

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- Fix to reusing conv

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- Lint fixes

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- Further lint fixes

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- Lint  fixes

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- lint fixes

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- Lint workaround

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* - Fix after review on including boost as third party header

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* - Fix after review. Name change to something more descriptive

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This reverts commit c38c7c56.

* link the libwbaes.so into paddle

* polish detail, test=develop

* try fix mac_pr_ci error, test=develop

* add compile option, test=develop

* fix ci error, test=develop

* ignore failed to find mac lib, test=develop

* change cdn to bj, cdn can't get the latest version

* trigger ci, test=develop

* temporary delete win32 lib linking, test=develop

* change https to http, test=develop

* turn compile option on to off

* turn compile option off to on, test=develop

* try lib compiled by gcc4.8, test=develop

* update lib version, test=develop

* link other lib, test=develop

* add setup config

* delete false, test=develop

* delete no_soname, test=develop

* recover so name set

* fix, test=develop

* adjust make config, test=develop

* remove link to wbaes, test=develop

* remove useless define, test=develop

* fix compiled
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* follow comments test=develop

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