Improvements to stdlib/3/_curses.pyi - take 3 (#1772)

* Added missing annotation for start_color() and wrapper() functions

* 1) Changed Optional types to be optional arguments (checked documentation and manual experiments to make sure I was doing it right)

2) Modified format to match CONTRIBUTING.md conventions

3) corrected a few missing return types or other mistaken type
annotations

stdlib/3/curses/__init__.pyi

@@ -1,9 +1,10 @@
 import _curses
 from _curses import *  # noqa: F403
+from typing import Callable, Any, Sequence, Mapping
 
 LINES: int
 COLS: int
 
 def initscr() -> _curses._CursesWindow: ...
-def start_color(): ...
-def wrapper(func, *args, **kwds): ...
+def start_color() -> None: ...
+def wrapper(func: Callable[..., Any], *arg: Any, **kwds: Any) -> None: ...