Pkgbase removing all third party pkgs nukes system

This should not be shipped. Removing all third party packages with pkg(8)
nukes the system, deleting everything but a few libraries. Pkgbase should
be handled by a seperate pkgbase(8) command. I belive that all packages
that make up a traditional base should have a flag that only lets them be
manipulated by pkgbase(8), while everything else can be manipulated by pkg,
even though the new command is a frontend for the same system. I also
belive that you should be able to add that flag to normal packages, for
example if I want ftpd back. I also belive this would be good for stopping
forced system updates when updating software, which is something I hate
about Linux.