Function manifold_split_by_plane

pub unsafe extern "C" fn manifold_split_by_plane(
    mem_first: *mut c_void,
    mem_second: *mut c_void,
    m: *mut ManifoldManifold,
    normal_x: f64,
    normal_y: f64,
    normal_z: f64,
    offset: f64,
) -> ManifoldManifoldPair