Merge pull request !4841 from zhanyuan/dev

replace frontend/operator/ops.h in backend with base/core_ops.h as
backend should not use any frontend-only primitive

Merge pull request !4836 from chenzupeng/master-lite

Merge pull request !4831 from byweng/add_test

Merge pull request !4760 from baihuawei/loss

Merge pull request !4823 from vlne-v1/I1RXHI-doc-parameter_api

Merge pull request !4825 from lyvette/parser

modify caffe parser

Merge pull request !4748 from wangminggui/master

Merge pull request !4828 from gongdaguo/revise_guard_and_add_modules

Merge pull request !4742 from jianghui/master

Merge pull request !4827 from fuzhiye/tmp

add testcase of st

Merge pull request !4829 from hangq/master

Merge pull request !4179 from ling/conv1x1

2.Supports large tensor allocation in PS mode.

Merge pull request !4686 from liuwenhao/master

Merge pull request !4792 from zhaoting/readme

Merge pull request !4754 from hexia/add_http_to_st_serving

Merge pull request !4833 from guozhijian/update_r0.6_to_r0.7

Merge pull request !4811 from wandongdong/master

Merge pull request !4816 from hexia/fix_log

Merge pull request !4817 from 王东旭/opencl_winograd_fixbug

Merge pull request !4806 from yao_yf/wide_and_deep_gpu_host_device

Merge pull request !4784 from yeyunpeng2020/master_cops_4

Merge pull request !4807 from hangq/master