Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Remove host.conf, and introduce a way to override the content
of selected files (at the moment /etc/host.conf and /etc/resolv.conf)
from /etc/rc.conf , so the number of places to customize is
reduced.

Major cleanup of PicoBSD startup scripts, which now should be
closer to doing "the right thing".

The structure is now the following:

* /etc/rc (from MFS) loads the rest of /etc and /root from
/fd and then from floppy (if present), then transfers control
to /etc/rc1

* /etc/rc1 loads defaults from /etc/rc.conf.defaults, tries to
set the hostname basing on the MAC address of the first ethernet
interface, and then sources /etc/rc.conf and /etc/rc.conf.local
for local configurations

* The rest of the startup process is then performed (rc.network and so on).

Everything except the initial /etc/rc (from MFS) can be overridden with
a local version loaded from floppy. But in most cases, you should only need
to customize the following files in /etc:

rc.conf rc.firewall hosts

Previously there were a number of inconsistencies in the calling
between files, and also a lot of clutter in rc.conf and rc.firewall.
Also, "rc1" was called "rc" and would overwrite the initial /etc/rc
from MFS, making it really hard to figure out what was going on in
case of bugs.