Add COWPtr and its unittest

fix ports_num_for_sparse defaut value in cluster_train doc

Release the middle layer's output memory

* create tensor in recv op

* static global function to global function

fix url in cluster_train_cn.md

fix compile error in profiler.cc

Stop gradient when pool_type=='max'

add GetPlaces operator

Enhance reorder_lod_tensor_by_rank_op to support Tensor

* "reuse ShareLoD with no regret"

* "removed base class shareLayout"

* "fix CI"

Add the parsing part for the profiling tool

fix capi package

* add rename guard

* add device_data_transform

* add device_data_transform_test

* modify GetExpectedKernelType

* update operator.run

* support test test_label_semantic_roles

* optimize code

* optimize code

* rename GetActualKernelType to GetExpectedKernelType

* fix chunk_eval_op and device_data_transform_test

* add is_same_place to place

* optimize code, refine rename_guard

* refine rename guard, add GetKernelTypeForVar

* optimize code

* add some log

* rename guard

* use sub scope to create var

* fix compile

* add IsInitialized for Tensor

* add VarIsTensor

* fix op_registry_test

* test

* tmp disable priority

* restore switch_kernel.md

* code clean

This can make it easier to locate error.

Bug fix when inserting fill_zeros_like_op.

Fix the output of conditional_block

update releasing doc

Fix doc of ParameterAttribute.

Fix comment to layers.fc