SDWF 0.53 release

[Stewart Gordon]

I'm on a Windows XP box at the moment, but won't be for long.  This has 
given me a chance to fix some incompatibilities between it and SDWF.  It 
seems that XP is somewhat more fussy than 98 in a handful of respects!

http://pr.stewartsplace.org.uk/d/sdwf/

Yes, I know the documentation's still at 0.52.  I've just not bothered 
installing Doxygen on this machine to date.  But hardly anything's 
changed, so I suppose it doesn't really matter that much.

Stewart.