PLEASE TEST: (laptop) autoconf at boot

Hi

I'd like to present some patches to teach FreeBSD to automatically
configure itself depending on what network it is started in.

The system depends on rcng, so 5.x is a requirement. The setup of
the various network profiles is done manually, after that, whenever
the laptop boots or wakes up from suspend, it detects where it is
located and configures itself accodringly. 

Please send all comments to freebsd-current so the discussion is not
scattered over several mailing lists.


How to patch:

cd /
fetch http://depot.fsck.ch/profile.diff
patch < profile.diff
rm /etc/rc.d/profile.orig /usr/share/man/man8/profile.8.orig
chmod 555 /etc/rc.d/profile
man profile


Features:
 - unattended startup, the laptop discovers automatically in what
   network it is started
 - read-only root partitions are supported
 - unintrusive. getting rid of everything profile-related is just a
   matter of turning it off in rc.conf and rm'ing the profile dir
 - everything under /etc is customizable per environment, not just the
   network


Drawbacks:
 - setup is a bit tedious
 - autodetection after suspend/resume does not work completely yet
 - during normal operation, changes to /etc are not straight forward
   anymore. see the manpage for details.


Notes:
 - I already have an idea about how to fix suspend/resume support. But
   as this involves some more changes to the system I'd like to hear a
   few opinions on the profile idea as a whole before starting with that.
 - The arguments for mdmfs/newfs are somewhat arbitrary. I just chose
   what seemed to work, someone with more insight might come up with
   a better sort of switches.