checkdiskconfig(): remove. It didn't make any sense to complain about
kernel keywords in user config files; it just made it more difficult
to convert. Now we ignore kernel keywords if we're not in kernel
mode.
get_empty_sd: initialize sectors.
free_drive: don't close if we don't have a vp. Maybe this will help
fix the problem that peter had, but I wouldn't count on it.
config_plex: If the plex is RAID-5, give it a rangelock structure.
start_config: Reset current drive, plex and volume so that a new
'create' command doesn't get long-dead defaults.
b7904c2bf9