Bug 30506

Related in part to 28926.

I've put the ipv6 scripts to real use now, and a few issues have crept up.  Using 5.69 initscripts.
I worked them out with Peter Bieringer, and after this I believe IPv6 will be in a very good shape.

1)  A big typo in init.d/network -- net-pf-10 alias is getting added to conf.modules every time
network is run.:

--- network~    Tue Feb 27 21:34:32 2001
+++ network     Sat Mar  3 12:53:12 2001
@@ -31,7 +31,7 @@
 
 # If IPv6 is explicitly configured, make sure it's available.
 if [ "$NETWORKING_IPV6" = "yes" ]; then
-       alias=`modprobe -c | grep net-pf-10 | awk '{ print $2 }'`
+       alias=`modprobe -c | grep net-pf-10 | awk '{ print $3 }'`
        if [ "$alias" != "ipv6" -a ! -f /proc/net/if_inet6 ]; then
                echo "alias net-pf-10 ipv6" >> /etc/modules.conf
        fi

2) lots of fixes and cleanups, among other things:
 * future support for external ipv6 address format changes (e.g.: how to notice '1:0::0' and '1::0' are the same) with external tool
 * actually kill the interface and all routes/addresses attached to it at 'ifdown dev1'.
 * if using two tunnels, make 'ifup sit1; ifup sit2; ifdown sit2; ifdown sit1;' equal 'ifup sit1; ifup sit2; ifup sit1; ifup sit2'
 * don't add static IP addresses to sitX devices N times if you run 'ifup sitX' N times.
 * change $variable -> "$variable" just to be sure (not strictly necessary yet)
 * filter out messages about route setting failing if you mistype 'ifup dev0' two times in the row
 * a few missing "'"'s (the same as mentioned in personal mail and #28926)
 * add LC_ALL=C to all route/ifconfig output that is grepped (as mentioned in personal mail)
 * probably something else I forgot.

ipv6calc is something that should be considered later

3) A short small guide how John Doe can set up an IPv6 tunnel for himself, an example of configuration file format. (Is this clear
&& graphic enough?)  This should probably go to %doc.