set en empty optimize block if pserver has no optimize block

Dist table support multi table

* fix GetTensorFromVar
test=release/1.1

* refine GetTensorFromVar
test=develop

test=develop

update doc to 1.1

add fused broadcast op unit test

test=develop

It seems that the blocking queue might be destroyed early than Run
method complete. It might because the Run method throw some unhandled
exception. However, it should be shared_ptr when multthread access an
resource. So change BlockingQueue as a shared_ptr.

test=develop

fix sequence_pad example error

* fix use_reader_alloc uts

* dist ut fixes test=develop

* update test=develop

* fix test for py3 test=develop

test=develop

remove the optimized but buggy implementation

test=develop

Fix dynamic_gru h_0 bug

Fix Mac Python3 CI job

Max Sequence pool optimization

remove with_inference option

test=develop

test=develop

Merge branch 'develop' of https://github.com/PaddlePaddle/Paddle into fix-pserver-crash-when-no-parameter

* feat(platform): lazy initialization of devicecontext in pool

Use std::async(deferer, []{...}) to lazy initialize DeviceContext in Pool

test=develop

* Add future includes

test=develop

test=develop

test=develop

increase test timeout coverage.

1.add position encoding  2.logloss in nn.py

test=develop

test=develop

test=develop