* add digamma, abs, trunc; test=develop

* fix bug and add diagonal; test=develop

* add name coverter; test=develop

* update tracer.py; test=develop

* add test case; test=develop

* fix bugs; test=develop

* fix selected_rows bug in C++ API

* add optional for C++ APIO

* data transform support optional

* remove data transform for optional vector<Tensor>

* adjust some format of funtcion

* fix empyt bug

* rename general grad infermeta func

* remove useless code

* Removed debug info

* Added automatic code generation for final state Eager Dygraph

* Modified backward yaml

* Added EagerUtils helper functions for final state CodeGen

* Adjusted CMakeFiles to support compilation for final state auto generated codes

* Added python-c code generation for final state Eager Dygraph

* Fixed minor issue

* Fixed yaml.load() method failure

* Fixed minor issues

* Refactored Python-C Attributes Parsing Functions

* Fixed minor issue with Python-C AddFunctions

* Adjusted python-level trace_op to accomodate final state Eager Dygraph

* Added Logs for final state Eager Dygraph

* Fixed merge issues

* Fixed minor issue

* add config of backward-api auto-gene

* fix compile bug

* remove wrong header

* rename grad_api to backward_api

* modify .gitignore