v2.1.2(Real kcptun random multiport)

Import real random multiport support

shadowsocks-android plugin config e.g.:

• mode=fast3;remoteaddr=server.example.com:10000-20000;autoexpire=3;dscp=46;crypt=aes-128;parityshard=2;rcvwnd=5120;key=your_secret_key;sndwnd=1024;mtu=1400;datashard=3;nocomp

Important parameters for random multiport:

• remoteaddr, remote server and port, the format is ip/hostname:minport-maxport, e.g. server.example.com:10000-20000, 1.2.3.4:1234-5678.
• autoexpire, auto expiration time(in seconds) for a single UDP connection, which is time to switch to new port(must exist and not 0).