Functions *_point now return Point instances instead of Rectangle ones.

I changed the return types of all the functions *_point so that they return a Point instead of a 1x1 Rectangle. I couldn't observe any regression, even though some functions (for example overlaps) now call their Point overload instead of their Rectangle overload.

I also added Point overloads to MapEntity's test_collision_with_border and test_collision_with_obstacles.