Merge cdrom 13xx handlers with main disk 13xx handlers.

Merge cdrom 13xx handlers with main disk 13xx handlers.

Most of the cdrom_13 code did the same thing as disk_13 - so merge
    them together.
Add definitions for 0xe0 (EXTSTART_CD) and 0x80 (EXTSTART_HD).
This changes the behavior for cdroms on 1315 and 1316 calls -
    previously 1315 returned an error and set ah=2, now it sets ah=1
    and doesn't return an error; previously 1316 returned ok, not it
    returns EPARAM.