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/positioned.py

@@ -0,0 +1,9 @@
+from typing import Protocol
+
+from dcs import Point
+
+
+class Positioned(Protocol):
+    @property
+    def position(self) -> Point:
+        raise NotImplementedError