automatic adding of routes when additional networks are specified

[naggie]

Currently adding extra routes via Networks is a manual step, unlike the automatically routed allocated IP. Adding (and removing) routes should be performed automatically on sync.

Note that wireguard is already told that a peer has a network via dsnetconfg - it then tells the kernel in turn. Routes must be manually added, for instance

sudo ip route add 10.182.0.0/16 dev dsnet