Improvements to Breeze plasma theme scrollbar/slider/progressbar color and contrast
This is a tweak to the Breeze plasma theme scrollbar/slider/progressbar to match my recent change for the application theme (reference: bug #444203, merge request !162). This change creates better contrast between the scrollbar, etc. and its groove. I have also altered the shading of the active scrollbar, etc. to match the application theme.
The scrollbar groove has also been made slightly transparent to better blend with the background when translucent plasma panels/popups are used.
