[patch] new cursor movement

[z9999]

What I am saying is there is no way to access to ground tile. So don't do that.

[wernieman]

I make a new compilerrun with the patch ... log at http://patches.simutrans-germany.com/

[Dwachs]

@wernieman: Thank you!

@all: updated patch, only internal things (cursor-overlay-color variable from einstellungen_t to umgebung_t) changed, no noticeable changes for players, no new compile needed.

[Dwachs]

this patch is now incorporated in rev 2455 and ready for massive testing in the nightlies:)