This was causing the parser to ignore the rest of the file after an
unknown option.

This avoids various unpleasant edge-cases.

This probably ensures that everything that can be done from the
command-line can be done from the configuration file.

This also adds options protocol-port and protocol-group.

This was causing the channel list to remain stuck at the old value
when we were rerouting.

Conflicts:
	CHANGES

Recent linux kernels (roughly 3.x) keep a routing cache for IPv6: each
time a host is contacted, a temporary /128 route is added. These
routes are visible using “ip -6 route show cache”.

Asking babeld to redistribute all IPv6 routes known to the host, using
"redistribute ip ::/0", causes it to announce and de-announce these
/128 routes frequently, leading other nodes to mark them as
unreachable (thus preventing communication with the host described by
the /128 route, even though less specific routes are available).

Interface_up can be called before an IPv6 address has been assigned to
the interface.  In this case, we need to down the interface again, wait
for a few seconds, then attempt to up it again.

Thanks to Julien Cristau.

Thanks to Julien Cristau.

This reverts commit 4229bea0.

The logic that attempted to optimise this away was buggy since it
wasn't taking IHU expiration times into account.  At any rate,
this optimisation is probably not worth the complexity.