SDWF 0.57 release

[Stewart Gordon]

It's about time I released a version of SDWF that compiles now that so-called DMD 1.00 is here.  (OK, I know, it's 1.004 now.)

So here it is.

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

Also added setPixel and getPixel to DC.

Stewart.