+ mobile (bool): if True then peer is "mobile" ie we assume it may
+ change its apparent IP address and port number without either it
+ or us being aware of the change; so, we remember the last several
+ port/addr pairs we've seen and send packets to all of them
+ (subject to a timeout). We maintain one set of addresses for key
+ setup exchanges, and another for data traffic. Two communicating
+ peers must not each regard the other as mobile, or all the traffic
+ in each direction will be triplicated (strictly, transmitted
+ mobile-peers-max times) and anyway two peers whose public contact
+ address may suddenly change couldn't communicate reliably because
+ their contact addresses might both change at once. [false]
+ mobile-peers-max (integer): Maximum number of peer port/addr pairs we
+ remember and send to. Must be at least 1 and no more than 5. [3]
+ mobile-peer-expiry (integer): For "mobile" peers only, the length
+ of time (in seconds) for which we will keep sending to multiple
+ address/ports from which we have not seen incoming traffic. [120]