FreeNAS Code

Improve/correct the top-level build script. In particular:
1. Fix the optimization which assumes that if the obj
directory is present then buildworld/buildkernel will
not need to be run. That is false if you provided the
-f option in the past, and as such would just generate
bogus images lacking new src features/patches.
2. Provide fine grained tuning of -f ports|all.
Rebuilding/not rebuilding ports has no effect today,
but it will in the future.
3. Print out a simple error message at the end if the
nanobsd build failed because nanobsd is extremely
quiet when things fail (except in terms of the exit
code).
4. Add a usage message and simple examples.
5. Update documentation.

Make forcing updates easier to grok and document them.

Add a hint pointing to the SF svn page for
those who may not be intimately familiar
with how SF looks/works.

A lot has changed in the last 8 months. Update the README
to reflect that.

Correct svn repo URL. Minor nit in advice fixed.

Upgrade build to 8.2-beta1

Document that i386 builds on amd64 work.

fix some typos, and update to include ISO.

We've moved! Yea!

Move up after last move added extra /ix.