* add pil backend

* hapi/model step learning rate on batch end. test=develop

* Make dynamic_decode support dygraph and expose to API 2.0
test=develop

* update info about BeamSearchDecoder and dynamic_decode

* remove all APIs in paddle.text, expose BeamSearchDecoder and dynamic_decode

* update example code

* delete test_text.py, decode.py, update some doc, fix example code float64

* delete decode import from paddle.nn

* fix unittest bugs

* use dygraph.Embedding instead of nn.Embedding, add paddle.enbale_static()

* update, correct doc

* move dynamic_decode, BeamSearchDecoder API to paddle.nn

* fix code style

* update unittest param, delete import pf text.py

* set dtype of beamsearchtest float64

* update example code of BeamSearchDecoder, dynamic_decode
Co-authored-by: NLiuChiaChi <709153940@qq.com>

* step lr_scheduler on epoch end in hapi/model.py fit. test=develop

* fix hapi load

* 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

* fix model bugs, inputs can be InputSpec instance

* correct error message

* add visualdl callback

* remove input requirment in dygraph Model

* correct unittest

* upadte save inference model in dygraph without input

* fix unittets for test_model.py

* solve conflicts

* solve conflicts

* delete http.log

* fix test_model.py bug, correct initialization of MyModel

* fix unittests bugs

* set paddle manual seed for unittest

* fix Model bugs, because inputs can be list or dict when it is provided.

* add random seed for test_export_deploy_model

* delete redundant codes, because  calls

* Code optimization, error information optimization

* refine vision models

* Remove dependency on nltk for paddle __init__.
test=develop

* Remove nltk.movie_reivew sentiment dataset to remove dependency on nltk.
test=develop

* reproduce summary api

* default open dygraph mode

* fix CI-Mac

* fix Mac-CI other unittest file

* fix CI-Py3

* fix test_communicator_geo and test_buffer_shared_memory_reuse_pass

* add enable_static to fix CI-Py3

* add enable_static to fix CI-coverage

* delete try except

* fix CIFAR & MNIST dataset. test=develop

* update model.save_inference_model

* update doc for _save_inference_model, delete useless class in unittests

* make users not be able to set model._inputs be None

* update usage of Model class in unittests

* fix bugs of _verify_spec

* fix bugs of _verify_spec

* add unittest to increase coverage rate

* delete http.log

* update doc for save, remove requirments and limitations for using

* update doc for class Model

* fix ports conflict when launching multi-nodes in paddlecloud;test=develop

* add DISTRIBUTED_TRAINER_ENDPOINTS env for cloud;test=develop

* fix summary rnn

* fix kl_div bug when input shape is [1] and reduction is batchmean

* fix conv output_size has no default value bug
* fix summary bug

* add summary for hapi

* replace fluid.optimizer.set_dict with optimizer.set_state_dict

* replace fluid.optimizer.set_dict with optimizer.set_state_dict

* add coverage rate

* Increase coverage rate, fix code style

* Increase coverage rate, fix code style

* add fit to generate optimizer.state_dict() to save .pdopt to increase coverage rate

* delete http.log

* Move hapi form paddle/incubate to paddle

* Remove vision/datasets/utils.py and clean code

* Add sample code for conll05

* Print pull path when saving model

* Fix sample code after paramter_list of SGD is changed to parameters

* Fix bug in wmt16 datase

* Move paddle/incubate/hapi/metrics to paddle/metric
* Add Precision, Recall and Auc metric