Perhaps this already exists, or if it doesn't perhaps someone could make it. Could a world generator plugin (maybe working off Multiverse) be created which generates a world filled only with caves? I.e. no above-ground section at all similar to the nether, but expanding all the way up to 256. Also would be cool if there could be custom underground tree things for a survival run through, and glowstone interspersed for lighting. Is this possible?