New World_map functions: has_crop() and has_mineral() return true if the given crop/mineral is at the specified location (if CROP_NULL or MINERAL_NULL is passed, they return true if there are ANY crops/minerals).  land_count() returns the number of tiles that are not ocean, and crop_count() and mineral_count() return the number of tiles that contain the specified crop/mineral (if CROP_NULL or MINERAL_NULL is passed, they return the number of tiles with ANY crops/minerals).