for Checkpoint save and load

Fix concat check

add elementwise floordiv, mod

* refine parallelExecutor
test=develop

* Polish op_handle
test=develop

* Remove unnecessary op_handle
test=develop

* Fix Travis CI
test=develop

* Fix fetch bug
test=develop

* Remove WaitInputVarGenerated

* Fix OpHandleBase::Run
test=develop

* debug
test=develop

* use origin fetch_op_handle
test=develop

* Revert op_handle_base.cc
test=develop

* Polish code
test=develop

* Fix OpHandleBase::Run
test=develop

* code refine

* test CI and CE
test=develop

* fix OpHandle::Run
test=develop

* refine AllReduceOpHandle
test=develop

* Polish code
test=develop

* refine fused_all_reduce_op

* add unit test in test_parallel_executor_seresnext
test=develop

Fix topk shape check

fix squeeze shape check

Fix sequence pad 2

fix matmul shape check

* Rewrite gradient ProtoMaker for affine_channel_op to remove the Output as the input.
* Add act in Python API to make the act can be in-place by layer_help.py

remove graph visualizer tool, which can be replaced by python IrGraph draw API

Fix lod reset

Approval rd api

* temoprarily disable the code of use kCUDNN, test=develop

* add TODO comment, test=develop

fix formula in dropout

* add resnet nccl2 test=develop

* test dist train test=develop

* update test=develop

* increase timeout test=develop

* test on CI env test=develop

* Add enabling quantization

test=develop

* remove unused (here) function

fix pattern maching conv2d with(out) ResidualData

* Enhance affine_channel_op infer-shape check