Timout handling for ixfrs as a client.

Timout handling for ixfrs as a client.

One complicating factor is that this is shared code, but auth and
rec do not agree on the definiton of the timeout value: auth states
it is a maximum idle time, while rec state it is the total xfr time.
While both apporaches make sense and in the end we would like to
enforce both, we now go for a more simple solution that respects
auth or rec behaviour based on a flag.