(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().

macros.h

@@ -110,14 +110,32 @@ extern const byte _ffb_64[128];
 
 static inline int FindFirstBit2x64(int value)
 {
+/*
 	int i = 0;
 	if ( (byte) value == 0) {
 		i += 8;
 		value >>= 8;
 	}
 	return i + FIND_FIRST_BIT(value & 0x3F);
+
+Faster ( or at least cleaner ) implementation below?
+*/
+	if ( (byte) value == 0) {
+		return FIND_FIRST_BIT((value >> 8) & 0x3F) + 8;
+	} else {
+		return FIND_FIRST_BIT(value & 0x3F);
+	}
+
 }
 
+static inline int KillFirstBit2x64(int value)
+{
+	if ( (byte) value == 0) {
+		return KILL_FIRST_BIT((value >> 8) & 0x3F) << 8;
+	} else {
+		return value & (KILL_FIRST_BIT(value & 0x3F)|0x3F00);
+	}
+}
 
 /* [min,max), strictly less than */
 #define IS_BYTE_INSIDE(a,min,max) ((byte)((a)-(min)) < (byte)((max)-(min)))