Make transformations colorspace-aware

[christeredvartsen]

Currently the image transformations doesn't really care too much about the colorspace of the images (sRGB / CMYK and so on), and this can cause some issues.

The main issues arise when the transformation takes some sort of color value as input, and applies this to the image.

The Imbo\Image\Transformation\Transformation::formatColor method is used for generating a hex-representation of the color, which causes imagick to handle the images as sRGB. If this method could take colorspace as an argument it could instead generate values such as:

• rgb(255, 0, 0)
• rgba(255, 0, 0, 1.0)
• cmyk(0.9, 0.48, 0.83, 0.50)

Some initial tests showed that when Imagick::newImage was given a color of cmyk(0.9, 0.48, 0.83, 0.50) it would create an image with the correct colorspace at least.

This issue is added to the 3.0 milestone, but should be back-ported to the imbo-2.x branch as well.