* wip

* add ref_by_trainer_id op

* ready to test

* fix ref inputs

* refine rpc_op_handle

* fix merge bug

test=develop

test=develop

test=develop

test=develop

test=develop

* enable pyreader use pin memory

* add py reader pin memory test test=develop

* Add affine grid generator.

* fix ffine grid.

* Add unitest.

* Add CPU kernel and fix unitest.

* Fix CPU kernel.

* Refine code.
test=develop

* Fix python api.
test=develop

* Update python api.
test=develop

* Fix comment.
test=develop

* Rename affine_grid_generator to affine_grid and enhence unitest.
test=develop

* Fix unitest.
test=develop

* fix dim0 in _load_slice_up_vars

* fix dim0 in _load_slice_up_vars, fix innershape in delete_var_op

* Revert "fix lookuptable in reduce strategy"

This reverts commit 0e722c5e

* add unit test for dist

* add unit test for dist, test=develop

* cancel revert, test=develop

test=develop

test=develop

* fix GetTensorFromVar
test=release/1.1

* refine GetTensorFromVar
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

test=develop

test=develop

remove the optimized but buggy implementation

test=develop

* 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

added depthwise conv mkldnn pass which for MKLDNN changes depthwise_conv operator to conv operator because for mkldnn this is the same api
test=develop

test=develop

test=develop

* fix sum_op's GetExpectedKernelType
test=develop

* fix ci fail
test=develop

test=develop

test=develop

test=develop