[magick-users] Saving using magickcore

[omicronpersei8 at imagemagick.org]

> does not actually produce a file at the end of it

We see a few mistakes.  Number 1, user MagickWand rather than MagickCore.
If you must use MagickCore,  you need to set the output image filename
at image->filename.  You also need to call SyncImagePixels() at the close
of your outer loop to ensure your pixels are updated.  Finally, your image
assumes a Q8 version of ImageMagick.  If you have a Q16 version you will need
to scale your pixels froom 0..255 to 0..65535.