fix a const_cast and avoid using stale program.

* test dist ut fixes test=develop

* fix cmake

* for test

fix mac ci test step, test=develop

* 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

My cool stuff

* wip multi process multi gpu dist training

* workable for p2p

* update test=develop

* change back env name test=develop

* fix alloc init

* fix cpu build test=devlop

* fix mac tests test=develop

* refine code

* refine test=develop

enable API check for readers

* layer fixes test=develop

* follow update test=develop

add more files to protected file list

* 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

Fix sequence_mask_op InferShape

Fix the bug that profiler cannot trace the nccl allreduce operator

test=develop

Revert "Add EstiminateFlops"

Add YOLOv3 loss operator for YOLOv3 model

add mac ci check on import

test=develop

test=develop

update is_test_pass and mkldnn_placement_pass

Implementing ngraph engine

test=develop

add ignore index for sigmoid cross entropy with logits op, test=develop

Add cudnn lstm

Stablize decorator test

Add EstiminateFlops

add the comment for CheckFile function

Update checkfile in datafeed

update CheckFile function in data_feed for ignore the space at the end of each line of data(for example, it may be added '\t' character to the end of the reduce task output when processes data by hadoop, which does not affect the correctness of the data). test=develop