VPN on VPN

[Jeremy Slater]

I noticed that with the standard vpnc scripts, connecting to a VPN
(VPN B) that is only available via another VPN (VPN A) causes a loss
of connectivity to VPN B.  This is because the route to the IP address
for VPN B is hard fixed to the system default gw, which is not (or at
least not always) routed through VPN A.

A simple fix seems to be to simply look up the route (route get on
OSX, ip route get on Linux I think) and add the host to that route
instead.  Is there a reason we don't do this?  I can submit a patch if
this sounds sane.

Jeremy