* fix pad outliers err

* fix pad api input type and doc

* fix example of pad

* add unittest for pad3d

* fix unittest

* fix error format

* fix pad doc

* support class center sample of PartialFC

* dygraph support more ctc grad scale

* scale for 1.x

* fix unitest

* fix unitest

* format code

* fix unittest

* fix log info

* unittest cov

* fix format;notest,test=cpu,coverage

* skip ctc_loss egs;test=cpu

* warpctc grad cov;test=coverage

* add dygraph test;test=coverage

* format;test=cpu,coverage

* format;test=cpu

* add api compat;test=cpu

* add cpu test

* rename

* rename

* fix

* fix test

* format

* eigen cpu

* eigen gpu grad pass

* cuda gpu pass

* format

* fix ci

* support margin loss (arcface, cosface, sphereface)

* fix paddle.optimizer test=document_fix

* fix paddle.optimizer test=document_fix

* fix bugs in paddle.nn.functional document test=document_fix

* fix bugs in paddle.nn.functional document test=document_fix

* fix bugs in paddle.nn.functional document test=document_fix

* fix bugs in paddle.nn.functional document test=document_fix

* cache core.ops, test=develop

* refine, test=develop

* opt dygraph python API, test=develop

* Fix unbind bug in manipulation.py

* update 2.0 public api in all left files

* reverse device.py all list;
fix some flake8 errors

* modify API nn.Bilinear's doc, test=develop

* enhance error message for conv

* fix ci coverage

* modify API nn.Bilinear's doc, test=develop

* speed up paddle.add paddle.nn.Linear, test=develop

* fix bug, test=develop

* Add deprecated warning info.

* Add unittest for deprecated decorator.

* Add warning info for tensor.grad

* [Rocm] fix tests of inplace_abn_op & grid_sampler_op

* [Rocm] fix tests of inplace_abn_op & grid_sampler_op