* lazy import for scipy

* rm unused check

* test=develop, rm pathlib

Remove NLTK requirements to avoid dependency security alert from Github Dependabot

* test=develop, rm netifaces

* rm dependence of cv2

* remove objgraph

* remove graphviz

* fix ut

set default python3,fix incompatible,cache dir for third party,unify error code,for windows (#26178)

* set default python3 for paddle windows,test=win

* set default python3,cache dir for third party,error code,test=win

* fix some incompatible

* fix some error

* set virtual environment,test=win

* test=develop,test=document_fix, remove the out args

* fleet_util move to paddle.fleet
Co-authored-by: NWuHaobo <wuhaobo1994@gmail.com>
Co-authored-by: Ntangwei12 <tangwei12@baidu.com>

* support nested if/else

* support to derivate returns the parameter list automatically

* polish tranform function of slice

* fix modify x.numpy()[i] slice function

* support to transform ast.node into callable function

* fix get_name_ids bug and add more unittest test=develop

* fix requirements.txt test=develop

* remove useless import statement test=develop

* Fixed version compatibility issues in param of function test=develop

* use decorater to test ast_to_func test=develop

* add textwrap.dedent for source_code test=develop

* polish code comment

* fix compatibility with python2 and python3 test=develop

* fix gast version error test=develop

* fix gast repo test=develop

* polish transfer_from_node_type code test=develop

* add nested_if_else unittest test=develop

* split IfElseTransformer test=develop

* specify gast version test=develop

* fix ast_to_func root type test=develop

1. Move AstNodeWrapper, StaticAnalysisVisitor to a new python file: static_analysis.py
2. Add basic node var type analysis

* add xly py35 dockerfile

* test=py35

* test=py35

* test=py35

* test=py35

* test=py35

* test=py35

* test=py35

* test=py35

* test=py35

* test=py35

* test=py35

* test dockerfile

* test=py35

* test=py35

* test=py35

* test=py35

* test=py35

* test=py35

* test=py35

* test=py35

* test=py35

* test=py35

* test=py35

* test=py35

* test=py35

* test=py35

* test=py35,test=develop,test=inference,test=document_fix

* refactor dygraph,test=develop

* fix failed unittest,test=develop

* polish code,test=develop

* check windows ci error,test=develop
try to fix windows ci error by np.allclose,test=develop

* polish vlog and profiler, test=develop

* try to fix preceding ops order,test=develop

* test transformer in windows ci, test=develop

* use python c-api to speed up tracer.trace,test=develop

* test=develop, fix docker with paddle nccl problem

* test=develop, add ut for debug string and gradient_accumulator

* test=develop, add tests for layer/gradient_accumulator/prepared_op

* test=develop, fix complie error for test_prepared_op

* test=develop, add more ut for dygraph

* test=develop, create API.spec for dygraph api change

* test=develop, refoctor name to make it easier to understand

* test=develop, refoctor name to make it easier to understand

* test=develop, fix multi-gpu failed problem , add Tracer tests, change PADDLEENFORCE to PADDLEENFORCE_EQ

* test=develop, fix ut failed on parallel se-resnext

* test=develop, change one more PADDLE_ENFORCE

As mentioned in this link, the last version of NumPy to support Python 2.7 is numpy 1.16.4.

remove pycpuinfo deps in core

* fix mac ci random fail
* use platform instead

* fix py-cpuinfo mac random fail
* differentiate version on windows

test=develop

update config for matplotlib, because python 3.6 is required by 3.1+

for py2:
matplotlib<=2.2.3 ; python_version<"3.5"
scipy>=0.19.0, <=1.2.1 ; python_version<"3.5"
nltk>=3.2.2, <=3.4 ; python_version<"3.5"

for py3:
matplotlib ; python_version>="3.5"
scipy ; python_version>="3.5"
nltk ; python_version>="3.5"

update requests version to >=2.20.0
for CEV-2018-18074

* support avx and noavx core

* add catch and give some log

test=develop

* fix build

test=develop

* add missing package

test=develop

* fix pybind name

test=develop

* fix import error

test=develop

* conbime noavx core

test=develop

* add requirements

test=develop

* fix unkown message

test=develop

* fix api spec

test=develop

* refine and clean

test=develop

* update

* pass dist ut

* follow comments

test=develop

* refine scripts

test=develop

* First pr of paddle slim.
1. Add framework of paddle slim
2. Add filter pruning strategy
test=develop

* Rename unitest to tests.
test=develop

* Add prettytable into requirements.
test=develop

* Change in_nodes and out_nodes to odered dict.
test=develop

* Remove distillation.
test=develop

* Fix API.spec
test=develop

* Fix unitest.
test=develop

* Fix unitest in windows.
test=develop

* Fix unitest in windows.
test=develop

* Fix unitest.
test=develop

* Hide some functions.
test=develop

* Fix python import in python3.5
test=develop

* Fix compress pass.
test=develop

* Fix unitest of test_dist_ctr.
test=develop

* Enhence flops.

* use os.path.join

* Fix pickle for python3
Fix log and comments.
test=develop

* 1. Remove feed_reader in compress pass
2. Fix cache reader
3. Rename CompressPass to Compressor
4. Add comments for distiller optimizer
5. Remove unused pruner currently
6. Add some comments.
7. Change API.spec
test=develop

* Fix pruning in python3.
test=develop

* Fix unitest in python3.
test=develop

* Fix format in python3.
test=develop