Support x.pe direct peer connection from Magnet link
v1: magnet:?xt=urn:btih:&dn=&tr=&x.pe=A peer address expressed as hostname:port, ipv4-literal:port or [ipv6-literal]:port. This parameter can be included to initiate a direct metadata transfer between two clients while reducing the need for external peer sources. It should only be included if the client can discover its public IP address and determine its reachability. Note: Since no URI scheme identifier has been allocated for bittorrent xs= is not used for this purpose.