Merge pull request !1779 from Xiaoda/fix-some-codestyle-warnings-of-w

Merge pull request !1772 from sunsuodong/var_init

Merge pull request !1387 from zhaoting/SSD

Merge pull request !1759 from chenweifeng/dropout

Merge pull request !1714 from huanghui/SoftmaxGradExt-fussion-pass

Merge pull request !1635 from JesseKLee/doc

Merge pull request !1780 from zhaozhenlong/op/lstm-open

Merge pull request !1758 from fary86/fix_return_parameter_directly_in_net

Merge pull request !1763 from jiangjinsheng/issue_invert

Merge pull request !1762 from zhangbuxue/support_convert_bool_scalar_and_tensor_to_number_tensor

Merge pull request !1721 from yoonlee666/master-wenti

Merge pull request !1685 from Xiaoda/fix-the-embeddinglookup-bug

Merge pull request !1768 from ms_yan/format_and_type

Merge pull request !1750 from zhouneng/add_vm_support_for_expm1

Merge pull request !1757 from lihongkang/lhk_master

Merge pull request !1747 from SJN/master

Merge pull request !1723 from jiangjinsheng/vm_SoftmaxGradExt

Merge pull request !1748 from caifubi/deal-warning-log

Merge pull request !1730 from wenchunjiang/fix_code_check

Merge pull request !1415 from kisnwang/support-mix-target

Merge pull request !1421 from rick_sanchez/pynative_new_4

Merge pull request !1744 from JesseKLee/btree_fix

Merge pull request !1745 from SanjayChan/master

Merge pull request !1749 from wukesong/readme_widedeep