* fix generate_proposal_labels in cascade-rcnn series model, test=develop

* fix example code & unittest, test=develop

* update code from review comments, test=develop

* modify cond while_loop to paddle.static.nn.cond

* modify crop_tensor to paddle.crop

* modify Variable to paddle.static.Variable

* remove nn.beam_search, nn.beam_search_decode, nn.gather_tree

* remove bpr_loss, center_loss, rank_loss, smooth_l1, teacher_student_sigmoid_loss, edit_distance, sampled_softmax_with_cross_entropy in nn.functional

* remove apis in nn.functional.learn_rate.py

* remove pool2d, pool3d, adaptive_pool2d, adaptive_pool3d in nn.functional

* remove apis in nn.functional.vision

* remove erf, soft_relu in nn.functional.activation

* remove apis in nn.functional.extension

* remove nn.functional.rnn

* remove hash from nn.functional.lod

* remove row_conv from nn.functional.extension

* remove one_hot, pad2d, pad_constant_like from nn.functional.common

* remove nn.gather_tree, nn.BilinearTensorProduct, nn.Pool2D, nn.Pad2D

* remove apis from optimizer.__init

* remove tensor.creation.fill_constant

* remove elementwise_mul in nn.functional.common and  modify to paddle.multiply

* remove  tensor.stat.reduce_mean

* remove reduce_all, reduce_any in tensor.logic

* remove apis in tensor.math

* remove apis in tensor.__init__

* remove has_inf, has_nan in tensor.search

* remove apis in framework.__init__

* remove apis in paddle.__init__

* remove apis in nn.functional.__init__

* modify removed alias apis to raw api in doc and unittests

* fix remove grid_sample bug

* modify removed alias apis to raw api in doc and unittests

* modify removed alias apis to raw api in doc and unittests

* modify removed alias apis to raw api in doc and unittests

* modify removed alias apis to raw api in doc and unittests

* modify removed alias apis to raw api in doc and unittests

* modify removed alias apis to raw api in doc and unittests

* delete alias api relastions in doc

* reserve paddle.compat, paddle.sysconfig

* remove unittest for paddle.reduce_all, paddle.reduce_any

* modify removed alias apis to raw api in doc and unittests

* recover paddle.save and paddle.load

* resolve conflicts

* fix sample code missing paddle.enable_static() bug

* fix sample code missing paddle.enable_static() bug

* fix to_string sample code error

* enhance collect_op for dygraph, test=develop

* enhance detection ops with lod, test=develop

* support none bbox left in generate_proposals, test=develop

* unfiy MultiLevelRoisNum, test=develop

* update core.ops, test=develop

* add op register for new input & output, test=develop

* Add `matrix_nms_op`

test=develop

* Make ci happy

test=develop

* Exit early when no detection

test=develop

* Fix license year

test=develop

* Output index as well

test=develop

* Match nms2 lod behavior and add `return_index` flag

test=develop

* Make CI happy

test=develop

* Fix wording

test=develop

* rewrite the sigmoid_focal_loss code example. test=develop

* fix spelling mistake in comments of code example.test=develop

test=develop

* add scale_x_y for yolo_box, test=develop

* refine eps in iou_similarity, test=develop

* test=develop fix generate_proposals

* enhance the error message of box_coder, test=develop

* enhance error message in box_decoder_and_assign

* enhance error message of collect_fpn_proposals

* enhance errror message of distribute_fpn_proposals

* enhance error message of multiclass_nms, test=develop

* enhance error message, test=develop

fix sample code diff for OP(retinanet_detection_output, retinanet_target_assign), fix `gamma` default value for OP(sigmoid_focal_loss) (#23744)

* fix sample code diff for OP(retinanet_detection_output, retinanet_target_assign), fix  default value for OP(sigmoid_focal_loss). test=develop

* fix float value. test=develop

* add int type for gamma and alpha.test=develop

* polish error message, test=develop

* fix if logic in dygraph, test=develop

* fix bug, test=develop

* enhance error msg. test=develop

* print invalid argment

* update comment, test=develop

* fix enforce not meet specification

* fix enforce not meet specification, test=develop

OP(retinanet_detection_output, retinanet_target_assign, sigmoid_focal_loss, deformable_roi_pooling) error message enhancement. test=develop (#23726)

* test=develop modify some op for dyg rcnn

* solve the conflict of ops with the same name. test=develop

This reverts commit abe3e690.
test=develop

* solve the conflict of ops with the same name. test=develop

* test=develop fix doc of detection's img_info param

Update iou_similarity op to support non-normalized bbox

* yolo_box OP add Attr(clip_bbox). test=develop

* Split some APIs from nn.py to loss.py

test=develop

* fix test_detection unit-test

test=develop

* refine 13 en doc

* Polish En doc for some APIs
* Update some comments and API.spec

Fix english doc api: sequence_slice, sigmoid_cross_entropy_with_logits, ssd_loss, DetectionMAP, detection_map (#20405)

* Fix english doc api: sequence_slice, sigmoid_cross_entropy_with_logits, ssd_loss, DetectionMAP, detection_map

* modify document of 11 APIs
test=develop
test=document_fix

* fix dtype to data type and description of name parameter