Improve privacy of LAN plugin
The LAN plugin updates its transport properties with the latest IP address whenever a connectivity change is detected. This may allow the user's contacts to tell when she's at a frequently visited location, either by recognising an address she used when they were nearby, or by inferring a pattern (e.g. the IP address she usually advertises at night probably represents her home network).
Instead of advertising a single current address, we could advertise a list of recent addresses. This would make polling more expensive - addresses that aren't valid for the current network aren't polled, but we can expect a lot of networks to use the 192.168.0.0/16 range, resulting in multiple polling attempts per contact.