Add expand operator

TensorSetConstant struct is used both in math_function.cc and math_function.cu. Somehow the release version can correctly handle it. But in debug version, set_constant_with_place() in math_function.cu uses the TensorSetConstant in math_function.cc and causes crash.

it is useful in gradient phase of an operator with block

It caused by a bug of std::call_once described in https://stackoverflow.com/questions/41717579/stdcall-once-hangs-on-second-call-after-callable-threw-on-first-call. It is likely caused by a deeper bug of pthread_once, which is discussed in https://patchwork.ozlabs.org/patch/482350/

add ROIPooling for Fast(er) R-CNN

fix openblas bug: undefined reference to pthread_atfork

update mkldnn design doc

* fix seq_concat with refactaring LoD

* fix failed unit test

* rename function name

add API for copying data from/to paddle matrix

IndicateDataType --> GetKernelType

fix typo in faq.

* first commit

* Python API for while op

* Python Unittest for simple while_op forward

* fix out to be list

* Fix UT

* VarType

* Fix several bugs

* Fix bug

* Fix bug

* Fix Bug

* Fix bug

* Fix unittest

* Remove debug log

* Add comments

* add PADDLE_ENFORCE

* while_grad_op first commit

* Add `BlockDescBind::FindRecursiveOrCreateVar()` and fix bugs

* refine code

* fix unittest bug

model inference

Remove fill_constant_batch_size_like_op.h and clean some operator codes.

Add chunk eval op

fix EQUAL unknown

* Adding operator assignment

* Adding documentation to layers.py

* Removing file from another PR

Feature/increase cpu

Remove unused g_main_program in tests

* Fix attribute naming for momentum_op

* Fix minor typo in comment

* Fix attribute name

* Fix names in test_optimizer

* Fix python wrapper

Add `lod_array_length` operator

remove unused INTEL_MKL_ROOT etc.

fix typo