TODO

   1
   2 - check superblock checksum in examine
   3 - report "chunk" or "rounding" depending on raid level
   4 - report "linear" instead of "-1" for raid level DONE
   5 - decode ayout depending on raid level DONE
   6 - get Assemble to upgrade devices if force flag.
   7 - --verbose and --force flags.
   8
   9 - set md_minor, *_disks for Create
  10 - for create raid5, how to choose between
  11    all working, but not insync
  12    one missing, one spare, insync