Support VIPS image processing beside GraphicsMagick/ImageMagick

[martinheidegger]

http://en.wikipedia.org/wiki/VIPS_(software)
https://github.com/jcupitt/libvips
https://github.com/dosx/node-vips maybe?
https://github.com/openzoom/node-deepzoomtools/blob/master/lib/vips._coffee