* remove no used fluid beam_search_decoder

* move Layer and related helper to paddle.nn.common

* modify Layer references from dygraph.layers.Layer to paddle.nn.common.layers

* stash changge

* remove fluid layer_object_helper, layers.py

* remove fluid layers init

* add setip

* fix unitest

* delete layers in fluid.dygraph

* merge paddle.tensor.stat,py

* fix circle import

* fix curcle import

* remove redundant in_dygraph_mode import

* revoce paddle.nn.common.* in fluid.__init__

* recovery nn.rnn

* paddle.frame use lazy import import paddle.jit to avoid circle import

* remove left dygraph.layers ref

* merge develop

* fix import error

* fix test error

* fxi merge error

* fix test fluid.Layer

* fix test error

* fix test error

* fix import error

* fix import error

* fix comments

* fix circle import

* fix rnn import error

* fix circle import

* add isort config

* isort all files

* fluid clean move out LayerList, ParameterList, Sequential from fluid

* copy Sequential from fluid to paddle.nn

* replace fluid LayerList,ParamterList, Sequential in unit test file

* add omit unit test file use paddle.nn.Sequential

* remove numpy and use paddle.uniform instead

* [CodeStyle][py2][U008] remove unnecessary args in `super()`

* remove remained args

* revert changes in test_pylayer_op

* Revert "revert changes in test_pylayer_op"

This reverts commit ff185a9ae738afac3b0264f61bde6c6b7f72e7c4.

* revert some changes in example code

* update config

* re-blacken python code

* temporarily disable date and diff_py_file

* skip a format

* use yapf to format all python file

* yapf exclude two unittests file for they rely on writing and reading file, and format will break them

* disable diff_py_file because too many diff files cause command following failed

* fix pipeline

* fix mp pp dp

* fix utest of hybrid parallel

* add utest for tuple

* add pipeline layer