* test=develop, fix docker with paddle nccl problem

* test=develop, hide no_support api and add ut for it

* fix regularizer lod bug; test=develop

* fix exception bug and one_hot expand; test=develop

* [DOC] Fix api docs, test=develop, test=document_preview

* [DOC] Fix api annotation: fluid.layers.tensor_array_to_tensor. test=develop, test=document_preview

* test=develop, test=document_preview

update MD5 of tensor_array_to_tensor

* BugFix: fix api comment of paddle.fluid.clip.GradientClipByValue
* test=develop, test=document_preview

* expose square
test=develop

* fix activation
test=develop

* Add square API
test=develop

* add necessary op

* code refine

* fix API.spec
test=develop

* fix unit test
test=develop

* add unit test sparse_grad_clip
test=develop

* fix API.spec
test=develop

* remove mac test for test_gradient_clip
test=develop

* remove selectedrows_mul_tensor
test=develop

* fix api format and examples

test=develop

* Update executor.py

test=develop

* Update nn.py

* Update nn.py

test=develop

* Update nn.py

test=develop

test=develop

* Yuyang fix global gradient clip

* Share LoDs

* Revert unnecessary changes

* Fix bug in sequence_slice_op

* hide operator API

* update

* update api.spec

* fix merge

* fix test

* hide program APIs

* fix merge error

* update

* remove block api

* remove clone_variable

* hide block inner apis

* update

* fix tests

* refine multi-thread CPU Parallel exe

* refine multi thread CPU Parallel exe

* Refine CPU version for ParallelExecutor

* add share_parameter_between_cards_

* Fix ParallelExecutor bug

* Fix unit test

* Fix parameter opt balance

* Fix with opti (param->grad)

* Add grad to op var

* Remove shard_param_between_cards

* "fix decode bug"

* "follow commnet"

* "fix error"

* "fix hook bug"

* fix based comment

* fix copyright

* fix based on comment

* add copyright hook

* add copyright hook

* refine copyright hook

* "test copyright hook"

* fix check style

* fix ci