0.81.1 of the i4b code - namely support of the I4B_VR_REQ
ioctl via the i4brbchX device.
Ppp controls the phone number, but idle timers and
SYNC/RAW decisions are still made by isdnd (in isdnd.rc).
This involves a new datalink state machine phase. The
``wait for carrier'' phase happens after dialing but
before logging in. The whole dial state should really
be abstracted so that each device type can deal with it
in its own way (thinking about PPPoE) - but that'll have
to wait.
The ``set cd'' symantics remain the same for tty devices,
but we now delay until we either get CD or timeout waiting
(at which time we drop the link if we require CD).
For i4b devices we always insist on carrier.
Thanks to hm@ for his help, and especially for pointing out
that I *don't* need to re-implement isdnd (that was a huge
waste of time !) :-]
