GIF tunnel on PPPoE reconnect / HE.net tunnelbroker IP DynDNS

[jimp]

I just pushed a batch of commits that should fix the known brokenness in the gif tunnels when a PPPoE line reconnects. The same problem may have hit others when a WAN reconnected, especially if the IP changed. It should behave better now.

I also added a DynDNS type to update your he.net tunnelbroker endpoints when your IP changes.

Between these two things, using he.net over a dynamic PPPoE connection should be workable now.