We were missing the luci packages...

This allows us to use separate .config files per target. Also, don't use
OpenWRT's feeds script anymore, but symlink the feeds ourselves.

Otherwise, `make cleanall` fails...

Explicitly re-build prepare-tmpinfo after the feeds have been installed, as it
isn't done automatically anymore since we have the gluon-tools target.

Also, more cleanup.

Introduce a new value "opkg_repo" in the site configuration.
The value should be a single domain name,
e.g. "http://opkg.services.ffki/attitude_adjustment/12.09/%S/packages".

Let the site configuration value script return 1 when
the requested value is not available.This enables us
to react on failures, so we can for example use a default
value.

With this patch the script will return with exitcode 1 if
the value is not found and no output on stdout. Otherwise
exitcode is 0 and the value is returned on stdout.

This *should* fix the build on non-Linux systems like MacOS X.

This should fix the TX power problems with the TL-WR841N/ND v9.

Only compile tested, might not work.

This allows us to drop our config mode patch.

This updates OpenWRT and rebases our patches.

Furthermore, the mac80211 module is removed as currently the Attitude Adjustment
main repo has a newer version (and some fixes that aren't in the backport repo).

Also, update odhcp6c from Barrier Breaker.