Add a python interface for Gelu.
    Add documentation for fluid.layers.gelu.

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* - BAtch norm mkl-dnn NHWC

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- compilation fix

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- UT fix

- cosmetics

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- Fix to Batch Norm MKL-DNN NHWC UT

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Conflicts:
	paddle/fluid/operators/batch_norm_op.h

* - Lint fixes

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As the title

* dygraph mode support linear lr warm up; test=develop

* add unitest for linear warmup; test=develop

* add input type check; test=develop

* fix type check assert error; test=develop

* change type error; test=develop

* fix profiler warning message in cpu profile mode test=develop

* test=develop, fix docker with paddle nccl problem

* don't expose numerous Tensor.set(), test=develop

* fix condition, test=develop

* fix float16 bug, test=develop

* feed should be Tensor or np.array, not Variable or number, test=develop

* use forcecast to copy numpy slice to new array, test=develop

* remove float16-uint16 hacking, test=develop

* add variable method to varbase and refactor to_variable to support return varbase

* support kwargs in varbase constructor

* add VarBase constructor to support default python args

* refine varbase initial method

* reset branch

* fix ut for change VarBase error info to PaddleEnforce

* cherry is parameter change before

* overload isinstance to replace too many change of is_variable

* rm useless files

* rm useless code merged by git

* test=develop, fix some ut failed error

* test=develop, fix test_graph_wrapper

* add some tests, test=develop

* refine __getitem__, test=develop

* add tests, test=develop

* fix err_msg, test=develop

* dygraph Embedding layer use lookuptable v2
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* fix test_nce
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* make DisableGlogInfo able to mute all logs in inference. 

* fix fill_constant_batch_size_like_op precious problem  test=develop

* modify the repo address of eigen and warpctc

* fix the eigen not work on windows

* fix the eigen and warpctc can't recompile

* fix PythonAPI test in Op unittest, test=develop
* fix unit tests that do not need to inherit OpTest, test=develop

* add data_type register CI test=develop

* add op add test case test=develop

* add test case for register op kernel test=develop

* fix shell script bug test=develop

* fix checkout branch test=develop

* remove test case code test=develop

* fix op_type.spec name test=develop

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* add overrider for virtual function; test=develop

* fix layer.h OutputName bug; test=develop

* add _get_all_register_op_kernels api test=develop

* refine usage of check_op_register_type test=develop

* add import in core test=develop

test=develop test=document_fix

* fix the compatiable problem between PY2 and PY3.

* add ut, test=develop

* add proxy, test=develop

* download dataset before test, test=develop

* add ernie-large test
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* add ernie large c++ inference test
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* support SelectedRows in dygraph, test=develop

* fix bug of _grad_ivar interface, test=develop

* add optest for support seletedrows, test=develop

* fix bug for gradient_accumulator in GPU mode, test=develop

* fix error when Selectedrows addto LodTensor in sorted_gradient mdoe in dygraph, test=develop

* refine and simplify gradient accumulator code, test=develop

* add optest, test=develop

* add optest and simplify code, test=develop

* fix bug for test_imperative_selected_rows, test=develop

* add optest for Coverage, test=develop

* fix gradient interface and simplify code, test=develop

* update api for gradient, test=develop

* fix ShareDim's bug in DygraphExecutionContext class, test=develop

* add optest, test=develop

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* set dim[0] to -1 if dim[0] < 0 and remove assertion to runtime, test=develop

* modify ENFORCE message, test=develop

* add validation for x.shape[0] > 0, test=develop

* add ut, test=develop

* add jeston compile support
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* refine the cmake
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* fix adam sample code bug test=document_fix

* fix sample code bug in scale test=document_fix

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