1. Revamp package installer to use new dependency lists and also
pkg_add's new `read from stdin' mode to prevent a copy of the package
from hitting the disk unnecessarily.
2. More fixes for running "not as init" - don't get upset if CDROM already
mounted, do the right thing instead.
3. If running as init, assume first-time install and _don't show the
(W)rite option in the fdisk screen.
4. Many other little tweaks, some of which will have to wait for fuller testing
until I can create a boot floppy (testing certain system-destroying
features of sysinstall can be a royal pain). Expect some more commits.
