(svn r2635) Fix: [ntp/misc] Improve the old pathfinder. Changed it to A* instead of Dijkstra.

- Benchmark shows that NTP is now around 10x faster than NPF.
  - Made IsTunnelTile macro to determine if a tile is a tunnel.
  - Added some useful debugging functions for making tiles red / getting accurate timestamps.
  - Remove old depot finding algorithm.
  - Disable warning for signed/unsigned comparisons.

tile.h

@@ -15,7 +15,7 @@ typedef enum TileTypes {
 	MP_VOID, // invisible tiles at the SW and SE border
 	MP_INDUSTRY,
 	MP_TUNNELBRIDGE,
-	MP_UNMOVABLE
+	MP_UNMOVABLE,
 } TileType;
 
 /* Direction as commonly used in v->direction, 8 way. */
@@ -95,6 +95,11 @@ static inline bool IsTileType(TileIndex tile, TileType type)
 	return GetTileType(tile) == type;
 }
 
+static inline bool IsTunnelTile(TileIndex tile)
+{
+	return IsTileType(tile, MP_TUNNELBRIDGE) && (_m[tile].m5 & 0xF0) == 0;
+}
+
 static inline Owner GetTileOwner(TileIndex tile)
 {
 	assert(tile < MapSize());