Replace payload string to unsafe.Pointer

[Bienne]

For example:
package main

import (
    "fmt"
    "github.com/thekvs/go-net-radix"
    "log"
    "unsafe"
)

type RateLimit struct {
    rate   int
    perSec int
}

func main() {
    rateLimits := make([]*RateLimit, 0, 0)

    rtree, err := netradix.NewNetRadixTree()
    if err != nil {
        panic(err)
    }

    rateLimit := &RateLimit{rate: 1000, perSec: 60}
    rateLimits = append(rateLimits, rateLimit)
    if err = rtree.Add("217.72.192.0/20", unsafe.Pointer(rateLimit)); err != nil {
        log.Fatal(err)
    }
    found, ptr, err := rtree.SearchBest("217.72.192.1")
    if err != nil {
        log.Fatal(err)
    }
    if found {
        rateLimit := (*RateLimit)(ptr)
        fmt.Printf("found: rate = %d, perSec = %d\n", rateLimit.rate, rateLimit.perSec)
    }

}