* support dlpack to tensor and implement python interface test=develop

* add unittest for _to_dlpack and from_dlpack test=develop

test=develop

* add expand_as op, test=develop

* add expand_as op,test=develop

* add expand_as op,test=develop

* add nn.py, test=develop

* delele paddle_enforce, test=develop

* refine py_reader exit, test=develop

* fix multiprocess_reader exception unittest, test=develop

* increase code coverage for legacy fluid.layers.py_reader, test=develop

* Fix docs of gru_unit and dynamic_gru.

Fix basic_gru in rnn_impl.py.

Add error messages for param_attr setting in layer_norm api.

Add int64 dtype for expand.

test=develop

* Reopen unit-tests of basic_gru/basic_lstm in rnn_impl.py.
test=develop

* Add unit test for layer_norm api.
test=develop

* Remove the deprecated gru doc fix. test=develop

* Fix basic_gru test coverage. test=develop

* Update API.spec. test=develop

* Update API.spec. test=develop

* Fix test_basic_gru coverage test. test=develop

* Update test_basic_gru in test_layers to use fluid.data
test=develop

* Update test_basic_gru for coverage. test=develop

* Refine error message of transpose.
* Fix transpose, multiplex, unsqueeze, unstack. test=develop, test=document_preview, test=document_fix

* fix the error message of zeros op
test=develop

* Fix unittest of zeros op
test=develop

* Add multihead fuse pass for ernie opt

* Refine softmax

test=develop

* Refine cuda kernel

* Refine cuda version

* Refine cmake

test=develop

* refine header file

* refine test case and pass
* refine comments

2. fix bug in backward.py: using fill_constant instead of fill_constant_batch_size_like
3. fix bug in ExpandGradOp.

test=develop

* modified group_norm's unittest for pass statement, test=develop

* fix group_norm's bug: scale or bias is None which causes segmentation fault, test=develop

* Fix the assign data check. test=develop

* Fix test_assign_op.py. test=develop

* Add ConvTranspose + BatchNorm fuse pass
test=develop

* Add tests for conv+bn and conv_transpose+bn passes
test=develop

* disable nccl test

* Update version.

* fix term core only

* fix transpiler error

* fix protobuf memory leak (#11177)

fix protobuf memory leak

* "change eigen mirror"

* refine en doc sequence enum pad expand mask d2s

* refine seq enum expand mask pad test=develop, test=document_fix

* remove cn char test=document_fix

* spec test=document_fix

* code style test=document_fix

* test=document_fix

* test=document_fix

* test=document_fix

* test=document_fix

* test=document_fix

* test=document_fix

* fix en docs of Layer and guard
test=document_fix, test=develop

* fix en docs of Layer and guard
test=document_fix, test=develop

* minor fix
test=document_fix, test=develop

* minor fix
test=document_fix, test=develop

* fix api.spec
test=document_fix, test=develop

* fix api.spec
test=document_fix, test=develop

* fix docs
test=document_fix, test=develop

* fix docs
test=document_fix, test=develop

* fix docs
test=document_fix, test=develop

* fix api.spec
test=document_fix, test=develop

* fix api.spec
test=document_fix, test=develop

* add forward doc
test=document_fix, test=develop

* add "s" for parameters
test=document_fix, test=develop

* update data feeder API sample, fluid.layers.data => fluid.data

* update API.spec

* fix doc of default_main_program, multiprocess_reader

* update API.spec

* fix comment

This PR fix the tag error in paddle_build.sh

* Refine the documentation of sums.

* Remove Chinese comments and update API.spec.

* Refine the description of input argument.

* Update API.spec.
test=develop
test=document_fix

Add API 'fluid.requird_version(min_version, max_version=None)' to check if the installed PaddlePaddle version is satisfied, test=develop (#20263)

添加API：fluid.version_required(min_version, max_version=None)，用于检查已安装的PaddlePaddle版本是否符合要求
无返回值，如果已安装的版本不在区间[min_version, max_version]，则抛出异常。
例：安装的版本为1.6.0，调用：fluid.require_version('1.5.0', '1.5.1')，则抛出异常：
Exception: VersionError: PaddlePaddle version in [1.5.0, 1.5.1] required, but 1.6.0 installed.

* Refine create_array api en doc

test=develop
test=document_fix


* Fix api doc example bug and polish square

test=develop
test=document_fix


* Refine comment

test=develop
test=document_fix


* refine API.spec

test=develop
test=document_fix

refine the en api doc of ones, zeros, reverse, assign, increment, hsigmoid and create_py_reader_by_data ops (#20343)

* refine the en api doc of ones, zeros, reverse, increment, hsigmoid and create_py_reader_by_data ops
test=develop, test=document_preview, test=document_fix

* refine eng doc for hsigmoid and create_py_reader_by_data ops
test=develop, test=document_preview, test=document_fix

* update API.spec
test=document_fix

* Fix the parameter name axis of reverse op in eng doc
test=develop, test=document_fix

* Update API.spec
test=develop, test=document_fix

* Refine eng doc of zeros, ones, reverse and assign op
test=develop, test=document_fix

* Update API.spec for assign, ones, zeros and reverse
test=develop, test=document_fix

* Fix data type of reverse op in eng doc
test=develop, test=document_fix

* Update API.spec for reverse op
test=develop, test=document_fix

* test=develop, add unittest  of seed failed work

* test=develop, add unittest  of seed failed work

enable cpu machine to run paddle model in gpu lib

* fix_conv_grad_grad

* fix_bug, test=develop

* support reshape doubel grad, test=develop

* fix reshape double grad, pass converage, test=develop

* fix review, test=develop

* fix_norm_model_average_bug

* test=develop

* refine comment test=develop

* refine comment test=develop

* refine eng doc for hard_sigmoid op
test=develop
test=document_fix

* refine the description of hard_sigmoid
 test=develop
test=document_fix

* update API.spec
test=document_fix

* Refine the decription of parameters of HardSigmoid op
test=develop, test=document_fix

* Update API.spec for hard_sigmoid op
test=develop, test=document_fix

* enhance embedding error message test=develop

* enforce .h error test=develop

* fix unittest code test=develop

* Fix fp16 dtype in embedding test=develop

* add import warnings test=develop

* Fix the error message of assign op
test=develop

* Refine input type checking for assign op
test=develop

* Refine unittest of assign op
test=develop