General changes:
- apply a similar 'style' as used in the installer scripts
- improve comments to be more to the point, remove where code is obvious
- document usage of functions if they have arguments
- rename variables where it improves readability
- replace really old-school shell code with more contemporary idioms
Other changes:
- No need to care about "autoboot" because netstart doesn't inherit the
positional parameters from /etc/rc anymore. /etc/rc executes netstart
instead of sourcing it since r1.439.
- Use simpler for-loop to process list of interfaces with ifstart.
OK halex@