1. Rename inputs and outputs
2. Add some comments

* add fp16 mul op support

* small fix

* fix bug

* small fix

* fix PADDLE_WITH_CUDA compiling issue

* reorg code

* test for pybind

* treate as float16 as uint16_t in pybind

* bind np.float16 to paddle float16

* small fix

* clean code

* remove redundancy

* fix mul_op test

* address comments

* small fix

* add is_float16_supported func

* "exported scatter to python"

* Revert ""exported scatter to python""

This reverts commit 38745a626c3f937bec836c92c98a76deadf0a03d.

* "polish scatter and export to python"

* "Refine nccl op"

* "refine code "

* "refine nccl code"

* fix nccl op unit test

* fix build error

* format code

* refine nccl related unit test

* fix build error

* add setGPUData

* clean up

* follow comments

* rm test_nccl.cu

* follow comment

* rm wait

* add memopt level

* add opt level for image classification demo

* clean code

* add delete op

* clean code

* test machine translation demo

* clean code

* clean code

* skip fill constant with force cpu

* clean code

* clean code

* refine code

* clean code

* fix bug

* Clipping bbox in the mAP evaluator calculation.

* Fix bug in detection_output and mAP calculation in SSD.

* Fix bug in detection.py.

* Fix bug in test_detection_map_op.py.

* MKLDNN pool2d OP kernel added

* conv2d and pool2d MKLDNN kernels renamed

* MKLDNN conv2d kernel refactoring

* fix mac build error

* override GetExpectedKernelType for cast op

* fix typo

* add cuda unittest

Fix sparse update memory error for distributed training