- fix library updates special cases: should note all potential library
packages as conflicts. Then save_old_libraries can split stuff off old
sets to keep libraries that are not in the new packages. There's only
one slightly tricky part, which concerns moving stuff that's not really
needed out of $set->{older}.
- in interactive mode, make it ask questions whenever the user could get
frustrated.
- finish pulling the pkg_add code into Add.pm/Update.pm.
- figure out when to continue after some errors, which should not stop a
full update, for instance... or ignore already installed packages (mostly
done).
- make sure all user-interface is done through a few functions, so that it's
easy to plug another interface in (mostly done)
- add needed annotations to handle updates correctly (to revisit)
- compare full package signatures during updates, to ignore stuff that's
different but older.
- mark that some older packages were found, cant_update should be different
from uptodate.
- if looking at replacements with a different name (based on the pkgpath),
stuff should still @conflict.
- don't close Location unconditionally while looking for updates. In most
cases, we're going to install this package right away, so we should try to
keep it open to avoid spurious ftp disconnects.