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.
+