* polish infer shape registry, test=develop

* modify some operators registry, test=develop

* add_dygraph_execution_context

* add dygraph infershape context and execution context; test=develop

* fix imperative bug; test=develop

* remove inputs outputs interface from execution context,
because it have same function with inputNames;
test=develop

* remove tracer_test ctest; test=develop

* fix split op bug; test=develop

* fix unitests bug; test=develop

* fix distribute test bug; test=develop

* fix ngraph compile bug; test=develop

* fix grad maker bug; test=develop

* fix load op bugs; test=develop

* fix operator.cc construct bug; test=develop

* remove useless name find in operator; test=develop

* add tracer_test; test=develop

* fix concat, split bug; test=develop

* remove tracer_test unitest; test=develop

* fix attribute check bug; test=develop

* add test code to fix converage; test=develop

* remove useless code, change check backward input in engin; test=develop

* unlock var type infer shape;test=develop

* add ShareAllLoD api; test=develop

* add dygraph infershape context unitest; test=develop

* remove increase and decrease lod in dygraph; test=develop

* addd override; test=develop

* fix increase descrease lod; test=develop

* fix paddle_enforce; test=develop

* disable lod op dygraph check; test=develop

* fix paddle enforce error; test=develop

* add comment for op_registry and OperatorBase; test=develop

* optimize the comment of op_registry; test=develop

* fix format of comment; test=develop

* fix format of comment; test=develop

* optimize the format of comment; test=develop

* optimize the format of the comment; test=develop

* optimize comment of op_registry; test=develop

* Add the check of lod_level between compile-time and runtime.
test=develop

* Fix bug in check_compile_vs_runtime.
test=develop

* Fix the check of output when it is dispensiable or intermediate.
test=develop

* Share lod of x to out in match_matrix_tensor op in compile-time.

* Implement GetLoDLevel in InferShapeContext.

* Set the default value of check_compile_vs_runtime to False and enable it in test_sequence_pad_op.
test=develop

* Enable check_compile_vs_runtime in test_match_matrix_tensor.

* Add the implementation of SetLoDLevel in InferShapeContext.

* Remove the implementation of IncreaseLoDLevel and call Get/SetLoDLevel instead.

* Remove the implementation of DecreaseLoDLevel and call Set/GetLoDLevel instead.

* Refine some ops and unittests.
test=develop

* Fix a typo.
test=develop

* Remove the check of var type, and change int to int32_t.
test=develop

* Add unittest for Get/SetLoDLevel.
test=develop

* Refine the InferShape of ReadFrom and WriteTo op, and add comment to explain why not call ShareLoD for runtime.
test=develop

* Add comment for ReorderLoDTensorByRank op.

* Add comment for lod_tensor_to_tensor_array op to explain why only call DecreaseLoDLevel for compile time.
test=develop

* ShrinkRNNMemory op should call ShareLoD for compile time.
test=develop

* Add the implementation of IncreaseLoDLevel and add the compile-time check of lod_level in InferShape of sequence_pool.
test=develop

* Refine the unittest of DynamicRNN.
test=develop

* Change PADDLE_ENFORCE to PADDLE_ENFORCE_NE.
test=develop

* add support to gcc8, add docker env test=develop

test=develop

* Add call stack info during runtime and compile time
test=develop

* Rename operator_call_stack
test=develop

* Add unit test
test=develop

* follow comment
test=develop

* disable memory_optimize and inpalce strategy by default, test=develop

* fix security issue
http://newicafe.baidu.com:80/issue/PaddleSec-3/show?from=page
http://newicafe.baidu.com:80/issue/PaddleSec-8/show?from=page
http://newicafe.baidu.com:80/issue/PaddleSec-12/show?from=page
http://newicafe.baidu.com:80/issue/PaddleSec-32/show?from=page
http://newicafe.baidu.com:80/issue/PaddleSec-35/show?from=page
http://newicafe.baidu.com:80/issue/PaddleSec-37/show?from=page
http://newicafe.baidu.com:80/issue/PaddleSec-40/show?from=page
http://newicafe.baidu.com:80/issue/PaddleSec-43/show?from=page
http://newicafe.baidu.com:80/issue/PaddleSec-44/show?from=page
http://newicafe.baidu.com:80/issue/PaddleSec-45/show?from=page

test=develop

* revert piece.cc, test=develop

* adjust api.cc,test=develop

* fix some grad op desc maker
test=develop

* fix grad op desc makers
test=develop

test=develop

test=develop

* code style fix, test=develop

test=develop

test=develop

test=develop

test=develop

test=develop

test=develop

test=develop

test=develop

test=develop

test=develop

test=develop

* CUDA kernel for density_prior_box_op.
* Support flatten to 2D.

Fix code to support cpplint syntax check

test=develop

avoid the default one that usually overwrites manually set ones

test=develop

test=develop

test=develop