fix links in readme

fix roi_perspective_transform_op.cc unused variable caused error on Mac

fix img_conv_group doc

Remove kwargs in elementwise layers and scale layer

disable memopt test

 remove kwargs of some activation api

* add ShareLoDs

* refine

* add Is EmptyVarName

* refine Sharedlod

remove the kwargs of elu,relu6,pow,stanh,hard_sigmoid and swish

Enhance eager delete and sparse Adam

Revert "Merge pull request #13431 from chengduoZH/refine_lod"

* Fix truncated normal.

* Fix.

Fix unstable selected_rows_functor_test.cu

* wip

* clean up

* should fix running with memopt

* add ut

* mark lr schedule op role

* hide lr_schedule_guard

* use op_role_var instead of ufind

* unify dist test name

* wip for py3 support

* fix var deref

* fix python3 mem_opt order

* remove comments

fix conflicts

use clone(for_test=True) replace get_inference_program

* Add roi perspective transform.

* Add roi_perspective_transform_op.

* Fix code style.

* Add python api and fix doc.

* Fix API.spec

* Fix python api.

* Fix API.spec

* Move src to detection.