(legacy) fix notices on IPv6.inc, we should replace this with https://pear.php.net/package/Net_IPv6/download/1.3.0b1 for 16.1 (but there are some other small changes as well there)

While there, make the script run from a secure shell as well.

via: https://forum.opnsense.org/index.php?topic=867.0

One of the benefits of having a stable/15.7 is that we can mop up
after it in master leading up to a clean 16.1.  :)

Keep a symlink on the true file system underneath MFS to keep
pkg(8) operating correctly all the time.

Spelling mistakes and some additional german translation

leaving out the excessive use of html tags in the descriptions.