doc/descriptions/canon_dr.desc: backend v5
- remove EOF ejection code
- add SSM and GSM commands
- add dropout, doublefeed, and jpeg compression options
- disable adf backside
- fix adf duplex
- read two extra lines (ignore errors) at end of image
- only send scan command at beginning of batch
- fix bug in hexdump with 0 length string
- DR-7580 support