(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().

npf.h

@@ -0,0 +1,128 @@
+#ifndef NPF_H
+#define NPF_H
+
+#include "ttd.h"
+#include "aystar.h"
+#include "vehicle.h"
+
+//#define NPF_DEBUG
+//#define NPF_MARKROUTE //Mark the routes considered by the pathfinder by
+//mowing grass
+
+typedef struct NPFFindStationOrTileData { /* Meant to be stored in AyStar.targetdata */
+	TileIndex dest_coords; /* An indication of where the station is, for heuristic purposes, or the target tile */
+	int station_index; /* station index we're heading for, or -1 when we're heading for a tile */
+} NPFFindStationOrTileData;
+
+enum { /* Indices into AyStar.userdata[] */
+	NPF_TYPE = 0, /* Contains an TransportTypes value */
+};
+
+enum { /* Indices into AyStarNode.userdata[] */
+	NPF_TRACKDIR_CHOICE = 0, /* The trackdir chosen to get here */
+	NPF_NODE_FLAGS,
+};
+enum { /* Flags for AyStarNode.userdata[NPF_NODE_FLAGS]*/
+	NPF_FLAG_SEEN_SIGNAL = 1, /* Used to mark that a signal was seen on the way, for rail only */
+	NPF_FLAG_REVERSE = 2, /* Used to mark that this node was reached from the second start node, if applicable */
+};
+
+typedef struct NPFFoundTargetData { /* Meant to be stored in AyStar.userpath */
+	uint best_bird_dist; /* The best heuristic found. Is 0 if the target was found */
+	uint best_path_dist; /* The shortest path. Is (uint)-1 if no path is found */
+	byte best_trackdir; /* The trackdir that leads to the shortes path/closest birds dist */
+	AyStarNode node; /* The node within the target the search led us to */
+} NPFFoundTargetData;
+
+/* These functions below are _not_ re-entrant, in favor of speed! */
+
+/* Will search from the given tile and direction, for a route to the given
+ * station for the given transport type. See the declaration of
+ * NPFFoundTargetData above for the meaning of the result. */
+NPFFoundTargetData NPFRouteToStationOrTile(TileIndex tile, byte trackdir, NPFFindStationOrTileData* target, TransportType type);
+/* Will search as above, but with two start nodes, the second being the
+ * reverse. Look at the NPF_NODE_REVERSE flag in the result node to see which
+ * direction was taken */
+NPFFoundTargetData NPFRouteToStationOrTileTwoWay(TileIndex tile1, byte trackdir1, TileIndex tile2, byte trackdir2, NPFFindStationOrTileData* target, TransportType type);
+
+/* Will search a route to the closest depot. */
+
+/* Search using breadth first. Good for little track choice and inaccurate
+ * heuristic, such as railway/road */
+NPFFoundTargetData NPFRouteToDepotBreadthFirst(TileIndex tile, byte trackdir, TransportType type);
+/* Search by trying each depot in order of Manhattan Distance. Good for lots
+ * of choices and accurate heuristics, such as water */
+NPFFoundTargetData NPFRouteToDepotTrialError(TileIndex tile, byte trackdir, TransportType type);
+
+void NPFFillWithOrderData(NPFFindStationOrTileData* fstd, Vehicle* v);
+
+/*
+ * Some tables considering tracks, directions and signals.
+ * XXX: Better place to but these?
+ */
+
+/**
+ * Maps a trackdir to the bit that stores its status in the map arrays, in the
+ * direction along with the trackdir.
+ */
+const byte _signal_along_trackdir[14];
+
+/**
+ * Maps a trackdir to the bit that stores its status in the map arrays, in the
+ * direction against the trackdir.
+ */
+const byte _signal_against_trackdir[14];
+
+/**
+ * Maps a trackdir to the trackdirs that can be reached from it (ie, when
+ * entering the next tile.
+ */
+const uint16 _trackdir_reaches_trackdirs[14];
+
+/**
+ * Maps a trackdir to all trackdirs that make 90 deg turns with it.
+ */
+const uint16 _trackdir_crosses_trackdirs[14];
+
+/**
+ * Maps a track to all tracks that make 90 deg turns with it.
+ */
+const byte _track_crosses_tracks[6];
+
+/**
+ * Maps a trackdir to the (4-way) direction the tile is exited when following
+ * that trackdir.
+ */
+const byte _trackdir_to_exitdir[14];
+
+/**
+ * Maps a track and an (4-way) dir to the trackdir that represents the track
+ * with the exit in the given direction.
+ */
+const byte _track_exitdir_to_trackdir[6][4];
+
+/**
+ * Maps a track and a full (8-way) direction to the trackdir that represents
+ * the track running in the given direction.
+ */
+const byte _track_direction_to_trackdir[6][8];
+
+/**
+ * Maps a (4-way) direction to the diagonal track that runs in that
+ * direction.
+ */
+const byte _dir_to_diag_trackdir[4];
+
+/**
+ * Maps a (4-way) direction to the reverse.
+ */
+const byte _reverse_dir[4];
+
+/**
+ * Maps a trackdir to the reverse trackdir.
+ */
+const byte _reverse_trackdir[14];
+
+#define REVERSE_TRACKDIR(trackdir) (trackdir ^ 0x8)
+
+#endif // NPF_H