* move fc from fluid to paddle2.0

* fix unit test

* fix some examples

* fix some examples

* move conv2d

* code-style and build bug

* restore c++

* code-style

* rm fluid init conv2d

* remove nn.conv2d

* modify doc

* remove dropout

* add inner function _elementwise_op_with_axis

* fix transformer_model

* polish API code

* remove elementwise_div/mul api

* delete API in __all__

* delete elementwise_mul completely

* polish elementwise_mul call

* polish internal api

* resolve conflict, fix rnn.py

* use non-inplace call

* delete elementwise_mul api test

* delete elementwise_mul api test

* clean elementwise_add/sub

* restore _elementwise_op_in_dygraph in nn.py

* remove pool2d

* modify slice infershape

* code style

* modify slice_unittest

* temp fix

* batch_norm api move

* code_style

* codestyle

* ci_static

* add __init__

* reset other change

* revert .cc

* add import batchnorm

* conflict and revert

* fix bug

* fix third conflict one day

* fix conflict

* fix conflict bug

* fix conflict bug

* modify api

* code_style

* modify doc

* add lost doc stable

* fix conflict bug

* ci lack of gpu

* mv accuracy and auc

* rm distributions

* rm get_places

* replace metric

* add isort config

* isort all files

* [remove fluid] under fleet meta_optimizers_wz

* [remove fluid] under fleet meta_optimizers_wz

* update

* [remove fluid] under fleet meta_optimizers_wz

* [remove fluid] under fleet meta_optimizers_wz

* [remove fluid] under fleet meta_optimizers_wz

* [remove fluid] under fleet meta_optimizers_wz

* [remove fluid] under fleet meta_optimizers_wz

* [remove fluid] under fleet meta_optimizers_wz

* [remove fluid] under fleet meta_optimizers_wz

* [remove fluid] under fleet meta_optimizers_wz

* [remove fluid] under fleet meta_optimizers_wz

* [remove fluid] under fleet meta_optimizers_wz

* [remove fluid] under fleet meta_optimizers_wz

* [remove fluid] under fleet meta_optimizers_wz

* [remove fluid] under fleet meta_optimizers_wz

* [remove fluid] under fleet meta_optimizers_wz

* [remove fluid] under fleet meta_optimizers_wz

* update config

* re-blacken python code

* temporarily disable date and diff_py_file

* skip a format

* [CodeStyle] remove all future import

* revert test_error.py

* restore future import in example code

* change fluid.mean to paddle.mean

* reverse some old code examples

* 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

* 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

test=develop

* refine dist train RPC deps

* clean up

* clean up

* fix ut

* remove input for fetch_barrier

* follow comments

* add async dist tests

* update delta

* fix transformer test

* refine rmsprop transpile

* update

* fix dist seresnet

* polish dist se resnext ut

* update

* update

* update

* avoid cpu initializer differ

* change to use executor for now

* update by comment

* remove lr decay use para exe, should fix para exe bug later

* update by comment

* enable dist se resnext

* small batch size

* wip add se-resnext test for 2x2 and parallel exe

* testing

* finish dist unitest 2x2

* update python interp

* fix gpu number

* make this test can run in parallel