* "merge random generator kernel and mul"

* "fix dropout"

* Implement multibox loss wrapper in Python API.

* Add some wrappers for SSD detection.

* Fix conflicts.

* Add unit testing for SSD loss wrapper.

* Update doc in Python API.

* Refine unit testing.

* Add more unit testing and update some interface arguments.

* refine inference_lib_dist after code move, and add it to docker/build.sh

* remove is_directory in inference_lib.cmake

* Add softmax_with_cross_entropy and smooth_l1 in Python API.

* Fix doc format.

* dynamic send/recv selected rows

* update by comment

* fix by comment

Fix #8368

* Fix constructor bug in mixed_vector

* Fix warnings

* Clean code

* Extract for-loop init. Make nvcc happy

* dist train support lr decay

* update by comment

* revert elementwise method creator

* delete comment

* Refine target_assign_op to unify the classification and regression targets assignment.

* Fix the unit testing.

* Fix conflicts.

* fix absolute include path

* Remove test_helper.h in old location

* update include path

move paddle/pybind/pybind.h to paddle/fluid/pybind/pybind.h, and cancel the test_parallel_op temporary

* Add unit-test and example

* Fix type error

* Fix unit test cases

* Fix init error for cudaplace

* Change unit-test options

* initial commit

* fix bug

* end of file fix

* address comments

* initial commit

* minor fix

* remove redundency

* address comments