repeat claim up to 3 times

[christf]

see: tcatm/l3roamd#14

In case of no response a claim should be tried up to three times, each after a short delay of about 1s if no response is received. Use the relinquished flag to determine when to stop.

[christf]

if there is no response, the client may be new.

[christf]

@t-8ch what do you think, is this worth re-introducing a taskqueue and a scheduler?
I ripped that one out previously to make l3roamd netlink-event-driven but it seems we still want to be able to schedule actions in the future....
ideas?

[t-8ch]

I don't see a way of having for example the kernel do the scheduling for us directly.
(I hoped we could use a reliable transport protocol, but that does not work in the multicast case).
Maybe we can reintroduce the previous scheduler?

[christf]

it is back now. Now it needs to be implemented after considering data structures. We do not want claims to happen 3 times, we want claims to happen up to 3 times. Since they are answered with an info packet, we can stop sending claims once we received an info packet for a claim.
At the same time, if a client is new, no info packet may be sent/received at all, so we need to stop repeating after a while.

[christf]

this is addressed by #30
Closing this issue as one ticket is enough to track this.