* doc: append PADDLE_ENFORCE rules to new_op_cn.md

* doc: polish writing

* refactor: polish doc based on advice

* link IR graph to analysis graph

* add clean code and update

* add infer_clean_pass

* add ir_pass_manager

* support fc fuse executation

* fix ir circle

* hide misc APIs

* update

* fix transformer test

* update API.spec

Reduce one level of inheritence.

add doc

* Add new_doc to develop branch

* Add pics of Anakin tutorial

* Update anakin_tutorial.md

* Delete anakin_fm_en.png

* Delete contri1.JPG

* Delete contri2.JPG

* Update build_and_install_lib_cn.rst

* Update compile_paddle_lib_cn.md

* Update compile_paddle_lib_en.md

* Update install_doc.rst

* Update install_doc.rst

* expose rank_loss python api

* remove block api

* remove clone_variable

* hide block inner apis

* update

* fix tests

* Design doc of fixed-point quantization.
* Update fixed point quantization desigin doc.
* Fix doc format.
* Update the backward part.
* Fix the grammatical.

* add_nccl2_dist_design

* update

* update by comments