Prieview Window has no color-management

[Winfried]

Since I learned how to use the preview window with a longer workflow, I recognize a missing colormanagement for the Preview Window.
Short test:
- open the ColorSpin Transformation
- open the Preview

[jsachs]

Fixed for next release. It was there but implemented incorrectly.

[tomczak]

The colour management seems to work now in Preview. One thing I discovered is that the Preview window recalculates (or at least repaints) itself every time the zoom is changed. The side effect of it is that if Clipped shadow/highlight buttons are hit, the Main Image Window shows the clipping immediately, but the Preview window needs to be re-zoomed to show the clipping (which is I think equivalent to hitting the Apply button in a current transformation upstream of the Preview window).

[jsachs]

For the next release, I made the Preview window respond immediately to changes in Show Clipped Highlights/Shadows and fixed a couple of other minor issues.