new bbox features (2D, 3D)

added stair-sanitizing code
adjusted walkers

grid/walk/GridWalkSimpleControl.h

@@ -64,7 +64,7 @@ private:
 		// TODO: WHY?! not only when going back to the start?
 		if (start.x_cm == possible.x_cm && start.y_cm == possible.y_cm) {
 			if (start.z_cm == possible.z_cm) {return 0;} // back to the start
-			throw 1;
+			//throw 1;
 			return 0.5;// stair start/end TODO: fix
 		}