Fix centering calculations using scaledHeight

[FSaurenbach]

Any reason not to use scaledHeight?

var settings = image(resourcesVfs["settings.svg"].readSVG().scaled(1, 1).render()) {
            zIndex(3)
            position(10, offsetY / 2)

            scale(0.2)
        }
        println("SETTINGS HEIGHT: ${settings.height}") // 400 (incorrect)
        println("SETTINGS HEIGHT: ${settings.scaledHeight}") // 80 (correct)
        settings.centerYBetween(offsetY, 0.0) // -197 or smth

centerYBetween does - height (minus) and then here in the snippet it will center the viewY on -197

BTW: If this gets merged, the same applies to animators (scaleTo()) too.