Simplify, fix, and merge copy module (#1132)

* Simplify and add missing types for copy module.

Error and error were missing.  I also removed the internal arg memo.

* Move copy module into 2and3

* Bring back internal kwargs

stdlib/3/copy.pyi

@@ -1,10 +0,0 @@
-# Stubs for copy
-
-# NOTE: These are incomplete!
-
-from typing import TypeVar, Dict, Any
-
-_T = TypeVar('_T')
-
-def deepcopy(x: _T, memo: Dict[Any, Any] = ...) -> _T: ...
-def copy(x: _T) -> _T: ...