[Mesh] Auto point to point

[Stuart Gathman]

I wanted to post a quick note on an idea I just had.  The routers can
try to create an openvpn/wireguard tunnel to a list of servers in the
neighborhood.  It will be a layer 2 link, with BATMAN running over the
link, so we don't need to worry about routing or bridge loops.  The
routers can use a common shared secret for the tunnel - or perhaps an
SSL key signed by a neighborhood CA (me).

This way, even if no neighbors are in reach, the router can connect to
the mesh.  I have tested this with openvpn (and manual tunnel config). 
I believe it is within AUP for ISPs as well.