* update docs

* follow comments

* fix typo

* "change operator interface"

* "move devicepool to device_context"

* "fix operator test"

* "fix op_registry Run interface"

* "net op passed. Need to fix nccl multi-Context"

* "add nccl group function"

* "add nccl group function"

* "fix gpu count exceed 32 error"

* "fix recurrent op, nccl op"

* "change the other operators interface with Place"

* "fix typo"

* "fix pybind"

* "fix device in python side"

* "fix pybind failed"

* "add init for test"

* "fix CI"

* add design doc on keys of operator kernel type

* follow comments

* Add design of switching kernel

* Follow comments

* multi cpu design

* update

* multi cpu executor to executor

* add graph converting

* use parallel operator to execute blocks with multi threads

* use auto-transpiler

* use auto-transpiler

* update

* update graph

* Polish executor design doc

* Adding few details

* Add fluid.md

* in response to comments from Tony and Abhinav

* add support new device doc

* add more info

* write versino.py

* add version py

* clean init py

* add istaged, major and etc... fields

* update

* update

* update

* Add survey of support of half in different CUDA versions

* small fix