Have netstart directly source sysconfig so that it stands on its own.
Do not source netstart in rc, run it with sh.
Rework the dangerous /etc/hostname.* so that it uses a variable with
a list of interfaces and a variable for each interface in that list.
The files /etc/hostname.* become obsolete with this change, the
information is now stored in /etc/sysconfig.
Source any /etc/start_if.${ifn} files so they can export things to
netstart (plans for future enhancements in this area.)
Obsolete /etc/defaultrouter, this is now down with $defaultrouter from
sysconfig.