scsi_debug: num_parts, ptype and (re-)scans

Changes in version 1.73:
- 'num_parts' parameter to specify 0 to 4 partitions
- 'ptype' to specify (or change via sysfs) SCSI peripheral device type
- support ability to increase the number of targets and/or luns then re-scan a scsi_debug host
- remove redundant trailing spaces

The patch is against lk 2.6.6 (or -bk[1-4]). The last change is superficial but substantially increases the size of the patch. So the attachment is gzipped.

The new facilties are described at:
http://www.torque.net/sg/sdebug26.html
A tarball of driver (version 1.73) is also there.

Doug Gilbert