* Remove the NGraph engine from PDPD repository
1. Each operator was removed from the operator's directory
2. Each test was removed from the unittest directory
3. The parallel executor support was removed from the PDPD
4. The CMake file was removed from the PDPD
5. The NG flags were removed from the repository
test=develop

* Remove ngraph from:
1. Cmake file
2. Python file
test=develop

* ngraph op test skip check grad ci, test=develop

* add no_grad_set value check in op_test, test=develop

* update ops list, test=develop

* remove skip_check in test_activation_mkldnn_op, test=develop

* modify test framework, test=develop

* fix test_fsp_op, test=develop

* up, test=develop

* up, test=develop

* up, test=develop

* add check for threshold, test=develop

* up, test=develop

* up, test=develop

* up, test=develop

* up, test=develop

* up, test=develop

* up, test=develop

* up, test=develop

* update, test=develop

* update, test=develop

* update, test=develop

* add is_empty_grad_op for OpTest, test=develop

* remove return in op_test teardown, test=develop
* add check_grad for fp64 and other type
* update white list

* test the equality between running-time and compiling time

* add white_list for compile_vs_runtime check test=develop

* add check of new-registered op on compile&runtime-lodEquality test=develop

* test=develop

* test=develop

* update white-list test=develop

* merge with new code test=develop

* fix code style test=develop

* test=devleop

* test=develop

* test=develop

* test=develop

* add more ops to white_list test=develop

* test=develop

* test=develop

* test=develop

* test=develop

* test=develop

* fix code_style: add comments test=develop

* test=develop

*use dtype to determine whether check_grade is needed, and delete useless class

* update op test framework

* 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

* use system allocator in unittests, test=develop

* fix op bugs, test=develop

* fix tensor copy bug when src and dst are the same, test=develop

* add global value getter setter, test=develop

* fix error messages, 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

* 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

* 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

* make OpTest check grad inplace even if forward has no inplace, test=develop

* do not run PE when enable_inplace is False, test=develop

* add conv3d cuda kernel for float16 type, test=develop

* refactor OpTest for inplace, test=develop

* add comments, test=develop

* update OpTest to support double grad inplace check, test=develop

* keep consistency of _calc_output function, test=develop

* update ngraph ops test=develop

* update unittest test=develop

* increase coverage test=develop

* fix bug of getting bool Flags from os.environ, test=develop

* add empty loss_name in CompiledProgram for inplace grad test, test=develop

* add pybind interface to get all inplace ops, test=develop

* enhance OpTest to check whether the consistency of operator when using and not using inplace, test=develop

* handle corner cases in op_test, test=develop

* support outputs without tensor holder_, like XShape in reshape_op, test=develop

* fix bug, some op has GradOpMaker, but actually no grad_op in OpInfoMap, test=develop

* use reshape_grad instead of reshape in FlattenGradOp, test=develop

* fix error debug dims info for variables like XShape, test=develop

* change computational order in sum_op to relieve computation difference using inplace, test=develop

* add inplace_atol to check group_norm, and skip inplace_grad for mkldnn, test=develop

* follow sneaxiy's comments, test=develop

* remove unused DefaultGradOpDescMaker in mkldnn op, test=develop

* fix memory overlapping of fetch var (return of executor.run), test=develop

* fix wrong usage of ParallelExecutor in op_test, test=develop

* remove useless parameter and simplify code

* avoid tensor destruct untimely, test=develop

* add testcase independent of OpTest, test=develop

test=develop