Also added a script to handle creation of GPT partitioned disk (with
GRUB config file). Block limit will be used to disallow potential access
to other partitions.
This is obviously more readable. If we ever run into a situation where
ref count churn is actually causing trouble in the future, we can deal with
it then. For now, let's keep it simple. :^)
Apparently you can boot from any MBR partition, not just the one labeled
as "bootable" or "active". The only ones you don't want to boot from are
the ones that don't exist.
