(svn r1751) - Feature: New PathFinder (NPF).

- Supports trains, road vehicles and ships.
	- Uses A* pathfinding (same codebase as the new ai).
	- Currently unlimited search depth, so might perform badly on large maps/networks (especially ships).
	- Will always find a route if there is one.
	- Allows custom penalties for obstacles to be set in openttd.cfg (npf_ values).
	- With NPF enabled, ships can have orders that are very far apart. Be careful, this will break (ships get lost) when the old pathfinder is used again.
- Feature: Disabling 90 degree turns for trains and ships.
	- Requires NPF to be enabled.
	- Ships and trains can no longer make weird 90 degree turns on tile borders.
- Codechange: Removed table/directions.h.
	- table/directions.h contained ugly static tables but was included more than once. The tables, along with a few new ones are in npf.[ch] now. Better suggestions for a location?
- Fix: Binary heap in queue.c did not allocate enough space, resulting in a segfault.
- Codechange: Rewritten FindFirstBit2x64, added KillFirstBit2x64.
- Codechange: Introduced constant INVALID_TILE, to replace the usage of 0 as an invalid tile. Also replaces TILE_WRAPPED.
- Codechange: Moved TileAddWrap() to map.[ch] 
- Add TileIndexDiffCByDir(), TileIndexDiffCByDir(). 
- Codechange: Moved IsTrainStationTile() to station.h
- Add: IsRoadStationTile() and GetRoadStationDir().

station.h

@@ -2,6 +2,7 @@
 #define STATION_H
 
 #include "sprite.h"
+#include "tile.h"
 #include "vehicle.h"
 
 typedef struct GoodsEntry {
@@ -224,4 +225,19 @@ uint GetNumRoadStops(const Station *st, RoadStopType type);
 RoadStop * GetPrimaryRoadStop(const Station *st, RoadStopType type);
 RoadStop * GetFirstFreeRoadStop( void );
 
+static inline bool IsTrainStationTile(uint tile) {
+	return IsTileType(tile, MP_STATION) && IS_BYTE_INSIDE(_map5[tile], 0, 8);
+}
+
+static inline bool IsRoadStationTile(uint tile) {
+	return IsTileType(tile, MP_STATION) && IS_BYTE_INSIDE(_map5[tile], 0x43, 0x4B);
+}
+
+/* Get's the direction the station exit points towards. Ie, returns 0 for a
+ * station with the exit NE. */
+static inline byte GetRoadStationDir(uint tile) {
+	assert(IsRoadStationTile(tile));
+	return (_map5[tile] - 0x43) & 3;
+}
+
 #endif /* STATION_H */