Properly support site.conf and don't hack local.conf

[schlomo]

While doing 08387b9 I realized (grep for local.conf) that there are places where we check local.conf for a configuration setting and there are other places where we write to local.conf.

Example: If users use site.conf to configure the use of DHCP in the rescue system then it won't work.

I think that this is very dangerous. Why not use the rescue.conf which is read after the local.conf for that purpose? Also, instead of greping local.conf for configuration items we should be sourcing in the ReaR configuration and use the value if set.

[gdha]

I'll improve the ./prep/GNU/Linux/21_include_dhclient.sh script some time later

[gdha]

@Reiner030 when you enhanced the rules of Debian packaging did you notice if the local.conf file got overwriiten?

[gdha]

added to the release notes so we can close this issue