Added CONTROL device that only does user-ioctl and nothing else;
Added protection so user-ioctl requires write access;
Clean up scsiconf.h a little. It needs more work.
Reenabled "SCIOCOMAND" ioctl.
Restructured so low level drivers can easily request retries.
Added preliminary fixed SCSI devices (should be revisited before 2.1)
Added "ssc" device that can have its' (HBA, ID, LUN) set via ioctl.