Very much needed developer-luvin for KIconEffect :)

I kept the same algorithms and this does not require Blitz, nonetheless this class was pretty nastified so this update pretty extensive. Due to this I also wrote a companion kiconeffect test to make sure everything works.

Changes so far include:

Don't use QColor just to get rgb components of a pixel.
Don't use pixel() and setPixel() when looping through an image.
Don't use the old fp-style alphablending, use integers.
Slightly more efficent math.
Check for premultiplied images.
Use KColorScheme, not KGlobalSettings.
Use QSysInfo and not defines

Still a little more work to be done but this should be much better.