(svn r2256) - Fix: Trains cannot find a depot when they are in a tunnel. (glx)

- Add: GetVehicleTrackdir() helper function.
- Codechange: Moved SortStruct from vehicle_gui.h to ttd.h, so the dependency from vehicle.h on vehicle_gui.h could be removed.
- Codechange: Typedeffed the VehicleTypes struct so it can be used as the type for Vehicle.type instead of "byte".
- Codechange: Removed prototype for VehicleSorter(), which had no implementation anymore and was never called.

vehicle.c

@@ -15,6 +15,8 @@
 #include "engine.h"
 #include "sound.h"
 #include "debug.h"
+#include "npf.h"
+#include "vehicle_gui.h"
 
 #define INVALID_COORD (-0x8000)
 #define GEN_HASH(x,y) (((x & 0x1F80)>>7) + ((y & 0xFC0)))
@@ -1707,6 +1709,35 @@ byte GetDirectionTowards(Vehicle *v, int x, int y)
 	return (dir+((dirdiff&7)<5?1:-1)) & 7;
 }
 
+byte GetVehicleTrackdir(const Vehicle* v)
+{
+	switch(v->type)
+	{
+		case VEH_Train:
+			if (v->u.rail.track == 0x80)
+				return 0xFF; /* Train in depot */
+			else if (v->u.rail.track == 0x40)
+				/* train in tunnel, so just use his direction and assume a diagonal track */
+				return _dir_to_diag_trackdir[(v->direction>>1)&3];
+			else
+				return _track_direction_to_trackdir[FIND_FIRST_BIT(v->u.rail.track)][v->direction];
+		case VEH_Ship:
+			if (v->u.ship.state == 0x80)
+				return 0xFF; /* Ship in depot */
+			else
+				return _track_direction_to_trackdir[FIND_FIRST_BIT(v->u.ship.state)][v->direction];
+		case VEH_Road:
+			if (v->u.road.state == 254)
+				return 0xFF; /* Road vehicle in depot */
+			else
+				return _dir_to_diag_trackdir[(v->direction>>1)&3];
+		case VEH_Aircraft:
+		case VEH_Special:
+		case VEH_Disaster:
+		default:
+			return 0xFF;
+	}
+}
 /* Return value has bit 0x2 set, when the vehicle enters a station. Then,
  * result << 8 contains the id of the station entered. If the return value has
  * bit 0x8 set, the vehicle could not and did not enter the tile. Are there
@@ -2076,5 +2107,3 @@ static void Load_VEHS(void)
 const ChunkHandler _veh_chunk_handlers[] = {
 	{ 'VEHS', Save_VEHS, Load_VEHS, CH_SPARSE_ARRAY | CH_LAST},
 };
-
-