* adapt test_collective_base.py for only two GPU cards available.
test=develop

* fix bug of issue #21259
test=develop

* add int8 kernel to lookup_table op and add dequantize op test=develop

* change paddle_enforce to paddle_enforce_eq test=develop

* change copyright and change some not suitable code test=develop

* remove debug log test=develop

* replace GetInputType with IndicateVarDataType test=develop

* fix EmptyGradMaker test=develop

* fix diff between cpu and gpu test=develop

* use memcopy when int8_t test=develop

Previously, CVM OP was only able to run in CPU. This PR implements its GPU kernel.
What's more, we improve the UTs about CVM OP.

* polish code details, test=develop

* futher polish hint msg, test=develop

pass the argument `allow_out_of_range` of one_hot op to c++ back end.

* fix fs_client_param bug， user can set this config through fleet_desc_file or fleet config
* test=develop

* general table

* add sparse table
test=develop

* no cvm
test=develop

* add no_cvm
test=develop

* add note
test=develop

* code style
test=develop

* code style
test=develop

* code style
test=develop

* code style
test=develop

* code style
test=develop

* add key of optimizer
test=develop

* solve pslib stop core
test=develop

* barrier
test=develop

* add notes
test=develop

* open dygraph op test, test=develop

* modify to_variable, test=develop

* modify input and output for dygraph, test=develop

* modify input and output for dygraph(fix bug), test=develop

* fix input processing of dygraph op test, test=develop

* fix bug, test=develop

* fix op test, test=develop

* fix forward bug for dygraph, test=develop

* fix mkldnn op test for forward, test=develop

* update nn.py for dygraph, test=develop

* fix crop_tensor_op, test=develop

* fix elementwise_mul_op, test=develop

* fix fill_op, test=develop

* fix some mkldnn op, test=develop

* open backward op test for dygraph, test=develop

* delete log, test=develop

* close backward op test for dygraph, test=develop

* fix bug for edit_distance_op and test_lstm_cudnn_op, test=develop

* fix optest backward bug for dygraph, test=develop

* fix optest backward bug for dygraph, test=develop

* close backward op test for dygraph, test=develop

* close backward op test for dygraph, test=develop

* open dygraph op test, test=develop

* fix op test for dygraph, fix GradOpDescMaker, test=develop

* fix bug for linear_chain_crf_op.h, test=develop

* remove log, test=develop

* remove log, test=develop

* remove log for op_test.py, test=develop

* remove log for op_test.py, test=develop

* fix bug for var_conv_2d_op, change PADDLE_ENFORCE, test=develop

* fix PADDLE_ENFORCE_EQ for hierarchical_sigmoid_op.cc, test=develop

* fix bug for test_increment_ngraph_op.py, test=develop

* fix lod for op test in dygraph, test=develop

* refactor op_test.py to reduce redundant code, test=develop

* fix lod optest, modify InputVar/OutputVar to HasInput/HasOutput, test=develop

* remove debug log, test=develop

* remove redundant code in base.py, test=develop

* fix some error in optest, test=develop

* fix ClearNoNeedBufferInputs function's bug for LoDTensor, test=develop

* refactor op_test.py, test=develop

* remove redundant writing, test=develop

* fix error(get tensor of the grad variable), test=develop

* fix test_concat_mkldnn test_conv2d_mkldnn, test=develop

* fix optest.py for get tensor of LoDTensor, test=develop

* fix optest.py for get tensor of LoDTensor, test=develop

* fix optest.py for get tensor of LoDTensor, test=develop

* fix some redundant code, test=develop

* reslove conflict and rewrite paddle error message, test=develop

* fix mkldnn include. test=develop

* fix mkldnn inlcude. test=develop

* fix fleet util bug in save paddle inference model
* test=develop

* add input type and input data type check for Print_op test=develop

* general table

* add sparse table
test=develop

* no cvm
test=develop

* add no_cvm
test=develop

* add note
test=develop

* code style
test=develop

* code style
test=develop

* code style
test=develop

* code style
test=develop

* code style
test=develop

* add key of optimizer
test=develop

* add control flow API: case. test=develop

* delete 'raise TypeError' in _error_message() and return a string. test=develop

* polish API document. test=develop

* support set model_filename and params_filename in post_training_quantization, test=develop

test=develop

* fix auc drop first commit test=develop

* update datanorm op

* update datanorm with enforce test=develop

* update test=develop

* update format test=develop

* update format

* update format test=develop

* add unit test test=develop

* update unit test test=develop

* update format test=develop

* update format test=develop

* update API description test=develop

* update API description test=develop

* update format test=develop

* fix codes as comments test=develop

* fix description as comments test=develop

* fix description as comments test=develop

* update codes.. test=develop

* polish jit trace codes, test=develop

* polish codes again by removing var_id, test=develop

* fix warnings oof gcc 8 compilation, test=develop

* fix boost::bad_get, test=develop

* refine PADDLE_ENFORCE, test=develop

* Fix TensorRT detection bug

1. Add new search path for TensorRT at tensorrt.cmake
2. Add better debug message
3. Fix the bug of detection of TensorRT version

In NVIDIA official docker image, TensorRT headers are located at
`/usr/include/x86_64-linux-gnu` and TensorRT libraries are located
at `/usr/lib/x86_64-linux-gnu`, so using `-DTENSORRT_ROOT` will
fail to detect TensorRT.

There is no debug/warning message to tell developer that TensorRT
is failed to be detected.

In later version of TensorRT (e.g. v6), `NV_TENSORRT_MAJOR` is
defined at `NvInferVersion.h` instead of `NvInfer.h`, so add
compatibility fix.

* Fix TensorRT variables in CMake

1. Replace `${TENSORRT_ROOT}/include` with `${TENSORRT_INCLUDE_DIR}`
2. Replace `${TENSORRT_ROOT}/lib` with `${TENSORRT_LIBRARY}`

Manually type path may locate incorrect path of TensorRT. Use the
paths detected by system instead.

* Fix TensorRT library path

1. Add new variable - `${TENSORRT_LIBRARY_DIR}`
2. Fix TensorRT library path

inference_lib.cmake and setup.py.in need the path of TensorRT library
instead of the file of TensorRT library, so add new variable to fix it.

* Add more general search rule for TensoRT

Let system detect architecture instead of manually assign it, so
replace `x86_64-linux-gnu` with `${CMAKE_LIBRARY_ARCHITECTURE}`.

* Add more general search rule for TensorRT

Remove duplicate search rules for TensorRT libraries. Use
`${TENSORRT_LIBRARY_DIR}` to get full path of libnvinfer.so

test=develop

* modified error message for conv and conv_transpose, test=develop

* modified doc of conv and conv_transpose op, test=develop

* modified the expression for error message, test=develop

* modified error message for group_norm op, test=develop

* modified detail of Attr(data_format) or Attr(data_layout)

* add ValueError in API doc for maxout op, test=develop

* add API switch_case. test=develop

add Nest

* modify code according to reviews:
1.Attr(branch_index) support 'uint8' and 'int64' besides 'int32'.
2.remove useless code.
test=develop

* replace fluid.layers.data with fluid.data and polish API document. test=develop

* Support  more ops in post training quantization, and save the output scale in quantized op.
* Update docs in post training quantization and qat 

* fix cache table bug
* add save_paddle_inference_model
* fix hdfs util bug
* test=develop

* copy some feasigns and corresponding embeddings from one sparse table to another
* copy all feasigns and corresponding embeddings from one sparse table to another
* copy all dense params from one table to another
* copy some local vars to other local vars

* friendly trace interface, test=develop

* refine TracedLayer, test=develop

* add some docs, test=develop

* add input type and dtype check template, and update some APIs check

* refine check template, and update some APIs check in nn.py

* update some APIs check in loss.py

test=develop