[Freeciv-Dev] (PR#2753) Fix unreal map position

["Jason Short via RT" <rt@xxxxxxxxxxxxxx>]

[rfalke - Tue Jan  7 18:16:47 2003]:

> 
> William reported this on IRC. Confirmed for 1.13.0 and CVS. Per:
> probably also contained in beta3 but the fix may be another one. With
> the Xaw client try to goto the explorer. If you move the mouse south
> you will get a assert for an unreal position. Fix is to copy the
> function body of the GTK client. Jason: this is another candidate for
> unification.

The problem, of course, is that normalize_map_pos doesn't handle for
unreal positions.

Using get_map_xy also allows the code to work with isometric view.

jason