We were using the Flags field instead of the AE field when parsing
compressed IPv4 prefixes in Update messages.  This bug shouldn't
trigger, since we never use compression with IPv4.

This avoids multiple config file entries for the same interface
causing an assertion failure.  Reported by Baptiste Jonglez.

Conflicts:
	CHANGES

It turns out that the rp_filter is only disabled if both all/rp_filter
and ifname/rp_filter are set to 0.  This sets and restores all of these
values explicitly, which fixes mysterious issues on distributions that
set rp_filter by default.

This avoids a crash when an interface is added both in the configuration
file and on the command-line.

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.