Add 'real' disk usage to db format so that sparse files are packed efficiently.
 - A sparse file takes up less disk space than the size of the file.
   Currently, lsbackups calculates enough space to include the whole thing on
   the CD.  With an ext2 filesystem there is no need to do this.  It only needs
   to reserve enough space for the actual disk usage.
 - This might not be true if the target image uses an ISO fs.  I should do some
   looking into this.

If a file has multiple hard-links then this is not handled efficiently.
lsbackups should only calculate space on the target filesystem for one
copy and actually preserve the hard-links.  This will save space and
make restore more accurate since the hard-links will still be there
after the restore.

Alan was here