peer.go
func (p *Peer) WriteTo(w io.Writer) (n int64, err error) {
	var n_ int
	wire.WriteString(p.Key, w, &n_, &err)
	n += int64(n_)
	return
}
func (p *Peer) WriteTo(w io.Writer) (n int64, err error) {
	var n_ int
	wire.WriteString(p.Key, w, &n_, &err)
	n += int64(n_)
	return
}
// WriteTo writes the peer's public key to w.