rescue: don't pull in sockets In rescue mode let's not establish all sockets, so that we don't end up starting a lot of additional services automatically. Instead of pulling in basic.target we now only pull in sysinit.target which pulls in local-fs.target and swap.target. That way rescue mode has all the really basic setup around, but normal services are not started and not autostarted either.

units: introduce new Documentation= field and make use of it everywhere This should help making the boot process a bit easier to explore and understand for the administrator. The simple idea is that "systemctl status" now shows a link to documentation alongside the other status and decriptionary information of a service. This patch adds the necessary fields to all our shipped units if we have proper documentation for them.

relicense to LGPLv2.1 (with exceptions) We finally got the OK from all contributors with non-trivial commits to relicense systemd from GPL2+ to LGPL2.1+. Some udev bits continue to be GPL2+ for now, but we are looking into relicensing them too, to allow free copy/paste of all code within systemd. The bits that used to be MIT continue to be MIT. The big benefit of the relicensing is that closed source code may now link against libsystemd-login.so and friends.

units: get rid of runlevel Names=, the symlinks in /lib/systemd/system are much more useful

units: make fedora/single.service standard and rename it to rescue.service

unit: introduce AllowIsolate= switch

units: rely only on isolate to remove running services when entering rescue/emergency modes

units: introduce emergency.target

unit: add [Install] section to various service files

shorten copyright header of configuration files

units: add distribution-specific units