* add infer_value for common math ops
* convert constant bool tensor to bool value

* do not infer value when encounter 0 as division

for while condition, do not unrool if condition is a tensor

Merge pull request !1851 from YuJianfeng/bn_cast

Merge pull request !1810 from sunsuodong/optimize_performance

Merge pull request !1842 from jiangjinsheng/issue_doc

Merge pull request !1823 from jiangjinsheng/vm_ConfusionMatrix

Merge pull request !1708 from chenjianping/host_reduce

Merge pull request !1843 from zhaozhenlong/fix-issues-scatter-and-lstm-comments

Merge pull request !1560 from guozhijian/change_zhwiki_CLUERNER2020_to_thirdparty

Merge pull request !1828 from yihuaijie/master

Merge pull request !1834 from Peilin/tf-reader-column-order-fix

Merge pull request !1809 from shibeiji/bert

Merge pull request !1825 from jiangjinsheng/issue_doc

Merge pull request !181 from JichenZhao/incubator

Merge pull request !1830 from wukesong/widedeep-time

Merge pull request !1827 from JichenZhao/issue_fix_branch

Merge pull request !1803 from Kang/master

Merge pull request !1817 from kisnwang/optimize-splitsort

Merge pull request !1819 from zhangbuxue/restricting_modify_non-Parameter_class_members

updates

more update

more work

more fixin

post rebase updates

clang formatting

code review recovery

ci fixes

updates

update

update

update

Merge pull request !1832 from JesseKLee/memleak

Merge pull request !1806 from Tinazhang/random-crop-error-msg

Merge pull request !1822 from fary86/codex_big_functions

Merge pull request !1802 from zyli2020/add_get_item_pass