* loosen the restriction of output_size in conv2d_transpose

* test and docs

* fix code style

* fix ci test error

* bug fix

* fix python3 issue

* hide program APIs

* fix merge error

* update

* Add sequence_expand_as_op

* follow comment

* Implement slice grad operator. #8130
* test slice grad operator and bug fix
* Fix pre commit style

* Enhence generate_proposal_labels_op
* Fix bug in generate_proposals_op
* Refine rpn_target_assign_op.
* by Bu Xingyuan, Wang Guanzhong and Dang Qingqing

* trainer auto wait pserver port ready

* add file

* fix docstring

* add option to not wait

* update api spec

* clean

* fix test hang

import os module to use os.environ in setUp()

* add ignore index

* update api.spec

* enhance softmax_with_cross_entropy

* Implement norm_op by CUDA instead of Eigen.
* Remove the commented code.

* Add intermediate

* fix flatten/squeeze/unsqueeze

* Considering compatibility issues, we could not fix the origin op

* follow comment

* reset the shape of XShape

* rmsprop optimizer support v1 mode

* typo

* optimize code

* refine code

* optimize unit test

* update test_rmsprop_op.py

* update formula of rmsprop

* optimize document

* update API.spec for RMSPropOptimizer

* add default value to check_output_with_place equal_nan