Update to OpenTTD 1.9.0-beta2

--HG--
branch : openttd

src/map_func.h

@@ -1,4 +1,4 @@
-/* $Id: map_func.h 24900 2013-01-08 22:46:42Z planetmaker $ */
+/* $Id$ */
 
 /*
  * This file is part of OpenTTD.
@@ -147,7 +147,7 @@ static inline uint ScaleByMapSize1D(uint n)
  * An offset value between to tiles.
  *
  * This value is used for the difference between
- * to tiles. It can be added to a tileindex to get
+ * two tiles. It can be added to a tileindex to get
  * the resulting tileindex of the start tile applied
  * with this saved difference.
  *
@@ -362,6 +362,18 @@ static inline TileIndexDiff TileOffsByDir(Direction dir)
 	return ToTileIndexDiff(_tileoffs_by_dir[dir]);
 }
 
+/**
+ * Adds a Direction to a tile.
+ *
+ * @param tile The current tile
+ * @param dir The direction in which we want to step
+ * @return the moved tile
+ */
+static inline TileIndex TileAddByDir(TileIndex tile, Direction dir)
+{
+	return TILE_ADD(tile, TileOffsByDir(dir));
+}
+
 /**
  * Adds a DiagDir to a tile.
  *