/// <summary>
/// Declares that the tiles in dest can be placed adjacent to the tiles in src, in the direction specified by (x, y, z).
/// (x, y, z) must be a valid direction, which usually means a unit vector.
/// </summary>
public void AddAdjacency(IList <Tile> src, IList <Tile> dest, int x, int y, int z)
{
RequireDirections();
AddAdjacency(src, dest, directions.GetDirection(x, y, z));
}
