(svn r2165) - Codechange: [NPF] Properly enummed NPF hash size, it is easily changable now.

- Codechange: [NPF] Improved the NPF hash calculation slightly.
- Codechange: [NPF] Increased hash size, should speed up somewhat.

npf.h

@@ -8,6 +8,13 @@
 //#define NPF_DEBUG
 //#define NPF_MARKROUTE //Mark the routes considered by the pathfinder by
 //mowing grass
+enum {
+	NPF_HASH_BITS = 12, /* The size of the hash used in pathfinding. Just changing this value should be sufficient to change the hash size. Should be an even value. */
+	/* Do no change below values */
+	NPF_HASH_SIZE = 1 << NPF_HASH_BITS,
+	NPF_HASH_HALFBITS = NPF_HASH_BITS / 2,
+	NPF_HASH_HALFMASK = (1 << NPF_HASH_HALFBITS) - 1
+};
 
 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 */