Register file timestamps
Remember the path tables in the primary descriptor
Put the size of the parent directory in the \1 entry, not own size
Allow the use of -b option without -a
Notes:
* Still missing the man page
* Filenames are still trimmed to 12 characters, because of
8.3 MS-DOS inherited compatibility (ISO9660 level 1);
also note that 7.4 or 9.2 filenames are accepted though
* Final . at end of filenames without extension is still missing
* VMS-compatible ;1 version suffix is still omitted
* Limit of 65,535 directories in path tables is not checked