Currently just uses the RG Unknown Dungeon map, which should be changed accordingly. The warps and stuff outside of basic entry aren't implemented.
Has a halved encounter rate compared to other maps, which matches the idea that caverns don't sustain much wildlife.
Mt Moon theme may not be used in the final product.
* Update sign to bg_event #289
* Rename warp to warp_event
* Replace object to object_event
* Move warp macro parameter from warp x, y, id, map to warp_event x, y, map, id