- check superblock checksum in examine DONE
- report "chunk" or "rounding" depending on raid level DONE
- report "linear" instead of "-1" for raid level DONE
- decode ayout depending on raid level DONE
- get Assemble to upgrade devices if force flag.
- --verbose and --force flags.

- set md_minor, *_disks for Create  - DONE
- for create raid5, how to choose between 
   all working, but not insync
   one missing, one spare, insync
- when RUN_ARRAY, make sure *_disks counts are right

- get --detail to extract extra stuff from superblock,
   like uuid  DONE
- --detail --brief to give a config file line
- parse config file. DONE
- test...

- when --assemble --scan, if an underlying device is an md device, 
  then try to assemble that device first.