More adaptation for pydcs updates.

This is as much as we can do until pydcs actually adds the py.typed
file. Once that's added there are a few ugly monkey patching corners
that will just need `# type: ignore` for now, but we can't pre-add those
since we have mypy warning us about superfluous ignore comments.

game/point_with_heading.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 from dcs import Point
 
 
@@ -7,7 +9,7 @@ class PointWithHeading(Point):
         self.heading = 0
 
     @staticmethod
-    def from_point(point: Point, heading: int) -> Point:
+    def from_point(point: Point, heading: int) -> PointWithHeading:
         p = PointWithHeading()
         p.x = point.x
         p.y = point.y