(svn r2473) - Add: VehicleMayEnterTile(), which checks if the tile owner of a tile is correct for a vehicle to enter it. Based upon glx's code.

- Fix: [ 1203769 ] [NPF] NPF tries to plan over bridges, through tunnels, over level crossings of other players. (glx)
- Codechange: Renamed TRANSPORT_MAX to TRANSPORT_END and added INVALID_TRANSPORT.
- Codechange: Moved IsLevelCrossing() from tile.h to rail.h
- Add: GetCrossingTransportType(), which returns the transport type (road, rail) of both tracks on a level crossing.
- Removed old TODO that was fulfilled already.

tile.h

@@ -18,7 +18,6 @@ typedef enum TileTypes {
 	MP_UNMOVABLE
 } TileType;
 
-/* TODO: Find out values */
 /* Direction as commonly used in v->direction, 8 way. */
 typedef enum Directions {
 	DIR_N   = 0,
@@ -116,9 +115,4 @@ static inline bool IsTileOwner(TileIndex tile, Owner owner)
 	return GetTileOwner(tile) == owner;
 }
 
-static inline bool IsLevelCrossing(TileIndex tile)
-{
-	return (_map5[tile] & 0xF0) == 0x10;
-}
-
 #endif