Import polyline rail tool patch v10b

http://www.tt-forums.net/viewtopic.php?f=33&t=57080

src/tilehighlight_func.h

@@ -14,6 +14,7 @@
 
 #include "gfx_type.h"
 #include "tilehighlight_type.h"
+#include "track_type.h"
 
 void PlaceProc_DemolishArea(TileIndex tile);
 bool GUIPlaceProcDragXY(ViewportDragDropSelectionProcess proc, TileIndex start_tile, TileIndex end_tile);
@@ -30,6 +31,10 @@ void VpSetPlaceSizingLimit(int limit);
 
 void UpdateTileSelection();
 
+void StoreRailPlacementEndpoints(TileIndex start_tile, TileIndex end_tile, Track start_track, bool bidirectional = true);
+void ResetRailPlacementSnapping();
+bool CurrentlySnappingRailPlacement();
+
 extern TileHighlightData _thd;
 
 #endif /* TILEHIGHLIGHT_FUNC_H */