moved all caches to Private; added protected accessor, and updated daughter classes
accordingly. Also renamed variables for consistency with other classes
optimization.
Added "NegativeText" brush, to optimize rendering of close buttons.
Renamed OxygenHelper to Oxygen::Helper for consistency with the other classes. (needs full update of workspace/libs/oxygen,
kstyles/oxygen and kwin/clients/oxygen, but this is already true for the above ...)
svn path=/trunk/KDE/kdebase/workspace/; revision=1125082