[arch-projects] [netcfg] Rethink systemd integration

Our current systemd units have a fatal flaw: They may fail because they are started before the needed devices show up. This patch series adds new units that fix that. However, the change is not transparent for the user and requires different configuration. I'd really like to deprecate netcfg.service, netcfg@.service and net-auto-wireless.service at some point, but that will break existing setups. I don't know if we should go ahead with this. Anyway, please comment on the patches.