merge to local

test=develop, update protobuf

refine fused emb seq pool

Fix pybind api arg0

* Enable cross_entropy operator for a ngraph engine
test=develop

* Update tests
test=develop

* Added PADDLE_ENFORCE for the batch_norm operator
test=develop

* Update the message about which format are supported right now
test=develop

* Correct the comment in control_flow.py.

* Correct the argument list of ops.
test=develop

* Update API.spec.
test=develop

* Skip op_callstack attr for all op apis.
test=develop

* Remove use_mkldnn and is_test from python api.
test=develop

* Remove use_mkldnn and is_test from op_proto_maker and hard-coding them in python when generating doc string.
test=develop

test=develop

test=release/1.3

test=release/1.3

Fix FtrlOptimizer's API comment

cherry picked modifies.

test=develop

* Add the CRFDecoding and LayerNorm's test case

test=develop

* Fix the size checking issue

test=develop

* Remove the remnant code

test=develop

* Add TestAllImpls and double support

test=develop

* Clean Code

test=develop

* Add benchmark test for LayerNorm & CRFDecoding

test=develop

test=develop

test=develop

* inplace group

* test=develop

Refine the doc of reshape, stack

Removed duplicated code

resolve #15724

Fix lstm possible leak

fix enforce

test=develop