Merge pull request !2474 from Chong/zc

!2418 add pretrain for lstm & vgg16 and remove lstm/vgg16/googlenet from directory 'mindspore/model_zoo'
Merge pull request !2418 from caojian05/ms_master_dev

Merge pull request !2460 from kisnwang/optimize-cpu-reduce-gradient

Merge pull request !2376 from Chong/zc

Merge pull request !2403 from JoyLvliang/session-code-review

Merge pull request !2446 from zhoufeng/xiu-ba-ge

Merge pull request !2443 from xiefangqi/xfq_fix_notice

Merge pull request !2401 from lianliguang/fix-code-review

Merge pull request !2241 from zhangzheng/accumulate

Merge pull request !2414 from limingqi107/master

Merge pull request !2439 from chenfei_mindspore/fix-bug-ascend-control-parser

Merge pull request !2438 from kisnwang/fix-mix-target-entry

Merge pull request !2440 from liuwenhao/master

Merge pull request !2306 from luoyang/pylint

Merge pull request !2386 from YuJianfeng/master

Merge pull request !2385 from Xiaoda/6-keep-sub-on-device-in-bprob-of-embeddinglookup

Merge pull request !2405 from chenzhongming/master

Merge pull request !2433 from qianlong21st/add_text_comment

Merge pull request !2413 from Xiaoda/7-auto-parallel-check-optimizer-ops

Merge pull request !2412 from jiangjinsheng/issue_fix4

Merge pull request !2427 from TronZhang/akg_default_on

Signed-off-by: Nzhoufeng <zhoufeng54@huawei.com>

Merge pull request !2417 from liuwenhao/master

Merge pull request !2177 from jiangjinsheng/vm_lin_space