Ability to add additional subnets to wireguard's AllowIPs

[yonghan]

I wonder if we can add additional subnets to wireguard's AllowIPs in wesher's configuration.

Right now wesher assigns a /128 or a /32 to nodes in the mesh.

However if there is a subnet behind the mesh, it would not be accessible by the nodes not physically connected to the subnet.

The solution I can think of is, wg showconf wgoverlay > wesher.conf then add the subnets in wesher.conf then wg setconf wgoverlay wesher.conf, but the work compounds as the mesh grows and I haven't really tried if it works.

Another use case would be adding ::/0 and/or 0.0.0.0/0 to a node and let the node act like a VPN gateway.

[costela]

This sounds like a duplicate of #28. Feel free to reopen if you think it isn't.