* fix peer rpc stop working because of mpsc tunnel close unexpectedly
* fix gui:
1. allow set network prefix for virtual ipv4
2. fix android crash
3. fix subnet proxy cannot be set on android
This patch removes Tarpc & Tonic GRPC and implements a customized rpc framework, which can be used by peer rpc and cli interface.
web config server can also use this rpc framework.
moreover, rewrite the public server logic, use ospf route to implement public server based networking. this make public server mesh possible.
