Here's a first cut at a CD-ROM driver. For now, it only supports SCSI
(that's all I can test, and I figured that ability to run on the Falcon was
the primary consideration :-)). To use it, rename the file to something
like "CDROML2.XFS" and copy it to the root directory of your boot disk.

(The "L" is the drive letter the drive should appear under, and the
"2" is the SCSI device number of the CD-ROM drive itself.)

Advantages of this over MetaDOS:

(1) Both Hisierra and ISO9660 support are in the same file, and they use
    the same drive letter; so you don't have to keep track of which kind
    of CD is which and which drive to use with them. (Also, there are fewer
    things to install :-).
(2) No CONFIG.SYS file is needed; I think users will find that a plus.
(3) I tried to make it slightly better at re-trying operations and recovery
    from errors. One of my CD's is quite flaky, and I find I can get more
    stuff from it using the .XFS than with MetaDOS.

Things that still need doing:

(1) Media change detection needs to be improved somewhat; sometimes it's
    necessary to explicitly hit ESC on the desktop in order to force
    the media change to be recognized.
(2) The SCSI code could be better at recovering from errors.
(3) Support for playing music would be nice.
(4) Multitasking gets killed while CD operations are in progress; something
    should be done about that.

Let me know about bugs that you find, and/or if you have some other features
you'd like to see.

Eric