whitespace
whitespace
whitespace
magick-get-image-blob: ignore length argument
filtertypes: rename to filtertype
magick-resize-image: take filtertype symbol for 'filter'
magick-resize-image: make 'blur' optional
pixelwands are not memory managed

The problem with putting a finalizer on a pixelwand is, I think, that
pixelwands are often passed into MagickWand where anything may happen with
them.  Chicken may try to garbage collect them when they are still needed.
It would be nice to come up with a better solution to this problem.
define-magick-image-op: small simplification/correction

Same correction to magick-resize-image.
magick-get-exception: more informative exception object
magick-read-image-blob: take a 'blob' instead of a c-pointer
examples/svg-demo.scm: an example program that displays an svg
magickwand.setup: corrections
don't free wands after MagickWandTerminus
svg-demo: simplification