Merge pull request !2971 from jjfeing/master

Merge pull request !2959 from hewei/decouple_signature

Merge pull request !2919 from limingqi107/master

Merge pull request !2957 from gukecai/fix-stream-bug

Merge pull request !2960 from YuJianfeng/master

Merge pull request !2949 from jiangjinsheng/issue_fix4

Merge pull request !2939 from Chong/zc

Merge pull request !2958 from ZPaC/add-ps-module

Merge pull request !2906 from zhangbuxue/support_implicit_type_conversion_for_pynative_mode

Merge pull request !2954 from Kang/optimization

This reverts commit 02dd305b.

Merge pull request !2951 from guozhijian/update_r0.3.1_release_notes

Merge pull request !2944 from wandongdong/master

Merge pull request !2779 from chenweifeng/ctcloss

Merge pull request !2765 from fary86/fix_large_for_loop

Merge pull request !2915 from Xiaoda/8-move-embeddinglookup-external

Merge pull request !2946 from EricZ/emtpy-tensor

Merge pull request !2926 from islam_amin/object_ops_cc_ut_floats

Merge pull request !2833 from nhussain/engine_validators

new test case

Name change for empty check

fixed random_apply tests

fix validators

fixed random_apply tests

fix engine validation

Merge pull request !2892 from tony_liu2/master

Merge pull request !2922 from ava/float_change

Merge pull request !2940 from zhangdengcheng/master

Merge pull request !2929 from jiangjinsheng/issue_fix4