Darken and lighten button colors for light and dark color schemes
The button coloration agreed to in the Breeze Evolution work wound up reverted in c4f93a4b because we were previously tinting the button color in the QStyle rather than changing the color scheme colors instead. This commit does that, restoring the intended button coloration for the Breeze Light and Breeze Dark color schemes as per and ongoing Breeze Evolution work.
Basically buttonsare now a bit lighter in Breezew Light, and a bit darker in Breezw Dark. This helps them stand out from the window a little bit, putting more emphasis on the interactive controls.