* Update csp.md

* Update csp.md

* Update csp.md

helper functions fetch_var and get_var

* Add proposed fluid syntax for select statement in Fluid's implementation of CSP

* Fix Typo

* Adding send and recv in design doc

* fix typo

* fixed code

* Adding threading

Refine prior_box_op

add independent sphinx tree for api

Add `make clean` in docker/build.sh

remove duplicated mobile index

Fix the error when sorted_key is none in profiler

* refine buffer channel

*  refine Receive and Send

* follow comments

* Adding more receivers less senders

* Added more receivers less senders

* Added more send

* Updated comment

* Fixed code style

* Fixing review comments

Buffered channel should notify both condition variables on close

Add depthwise conv op gpu

simplify shape inference code

Refine elementwise_op

Add v2 dist benchmark vgg

 Add multi-class non-maximum suppression operator.

Reclassify and change of V2 API documentation structure

add mine_hard_examples operator

add box coder op