RLMeshSpace
A space: a spec plus its sampler. RLMeshBox, RLMeshDiscrete and RLMeshDict are the same handle (pass a Dict to rlmesh_space_* without a cast); clone and free every kind with rlmesh_space_clone / rlmesh_space_free. A typed accessor (rlmesh_box_low, rlmesh_discrete_n, rlmesh_dict_get, ...) on a handle of another kind returns RLMESH_ERR_TYPE; check rlmesh_space_kind first.
typedef struct RLMeshSpace RLMeshSpace