Major version changes since version 0.01
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0.10 - early version 30 Mar 2013.
0.15 - Improve sprites for application directories
       Handle image files properly 09 Apr 2013               
0.16 - More help text 18 Apr 2013                            
0.18 - Add directory date suppression
       Ensure CSV file is correctly sorted.
       Trap error &F (subscript range) - increase WimpSlot
       Trap error &14219 error reading data 04 May 2013
0.19 - Improve directory date suppression by forcing
       bits 8 to 19 of the 'load address' read for
       a directory object to 'FFD' in this case.
       When a file will not open (for example where
       read access is barred) then don't calculate
       the crc (which would generate an error) but just
       set CRC to FFFF in this case 09 Aug 2013.
0.20 - CSV file output is now a proprietary format similar
       to a 'CSV' file (so that it can be loaded into Excel)
       but with constraints to ensure internal consistency.    
       12 Aug 2013.
0.21 - added SHIFT-drag of a directory which acts as if a
       file at the same level had been dragged, i.e. lists
       the directory it resides in (allows a directory
       or drive containing only directories to be listed).
     - drag of an image FS file now acts as a file drag
     - listing of a root directory now shows disc name vice $
     - click on icon bar icon opens display window
       04 Mar 2014
0.22 - add optional formatting commands '|Command' at start of
       'DiscCat' file 24 Oct 2014.  
0.24 - add SHIFT-drag of a second 'DiscCat' onto a filer
       display to hide all matching files 19 Feb 2016.
0.28 - initial display to show only top level contents,
       ranked by size. Large discs now supported.
       27 Mar 2021 
0.29 - reinstate shift-drag of 'DiscCat' file 28 Mar 2021.
0.30 - allow saving of formatting commands, include
       datestamps where file sizes are not known - for
       example after loading a DiscCat file 29 Mar 2021.
                 
C. K. Hall   29th Mar 2021.

