Fold in my latest changes to the worm driver.

This makes it sorta usable, just for my ``proof-of-concept'' Perl
script i've been posting to freebsd-scsi. The driver will be
overhauled further, this is just to provide Jordan with a base to
perform testing of his own with his HP burner. Use entirely at your
own risk, expect a bunch of misburnt CD-R's when using it already in
this very green stage.

Note that by now the driver will only work when the CD-R has already
been in the drive at boot time.