fix prefix and embedded config detection on fedora 18

Fedora patch grub-2.00-for-ppc-include-all-modules-in-the-core-image.patch,
added in RPM grub2-2.00-10, shifts core.img object types numbers,
which prevents BIS from correctly displaying embedded config and prefix.

Unfortunately we have no way to really detect distribution and
RPM version so add some heuristic and detailed explanation for anyone
willing to improve it.

Modules type 1, 3 and 4 are relatively easy to identify. Module type 2
needs to distinguish between ASCII text and unknown memory disk content,
so this patch is using `file' and leaves it as last resort (normally at
least prefix should be present).

Assitionally patch fixes zero padding for prefix and embedded config,
which can be longer than one character.

Signed-off-by: Andrey Borzenkov <arvidjaar@gmail.com>
correctly truncate border line after embedded config

If embedded config is the last item printed for grub2, BIS adds final dot.
This makes it later not truncate last 5 dashes when formatting output.
Include optional dot in pattern.

Signed-off-by: Andrey Borzenkov <arvidjaar@gmail.com>