Function rrt::dual_rrt_connect

pub fn dual_rrt_connect<FF, FR, N>(
    start: &[N],
    goal: &[N],
    is_free: FF,
    random_sample: FR,
    extend_length: N,
    num_max_try: usize
) -> Result<Vec<Vec<N>>, String>where
    FF: FnMut(&[N]) -> bool,
    FR: Fn() -> Vec<N>,
    N: Float + Debug,

search the path from start to goal which is free, using random_sample function