Add missing enum attributes (#1195)

Fixes #854 (unless there's more I'm missing).

Author: JelleZijlstra

stdlib/3.4/enum.pyi

@@ -1,11 +1,16 @@
 import sys
-from typing import List, Any, TypeVar, Union, Iterable, Iterator, TypeVar, Generic, Type, Sized
+from typing import List, Any, TypeVar, Union, Iterable, Iterator, TypeVar, Generic, Type, Sized, Reversible, Container, Mapping
 
 _T = TypeVar('_T', bound=Enum)
 _S = TypeVar('_S', bound=Type[Enum])
 
-class EnumMeta(type, Iterable[Enum], Sized):
+class EnumMeta(type, Iterable[Enum], Sized, Reversible[Enum], Container[Enum]):
     def __iter__(self: Type[_T]) -> Iterator[_T]: ...  # type: ignore
+    def __reversed__(self: Type[_T]) -> Iterator[_T]: ...
+    def __contains__(self, member: Any) -> bool: ...
+    def __getitem__(self: Type[_T], name: str) -> _T: ...
+    @property
+    def __members__(self: Type[_T]) -> Mapping[str, _T]: ...
 
 class Enum(metaclass=EnumMeta):
     def __new__(cls: Type[_T], value: Any) -> _T: ...