Make KStyle honour KDE wide single-click behaviour

[Craig Drummond]

> Ok, I hope I understood everything correctly and the attached patch is
> ok. Note that I didn't include the changes from Craig (except the
> icons-on-pushbuttons) as those where using KIconLoader, which means
> needing a lot more than just a config()->group().readEntry() to work
> properly.

I wouldn't do the icons-on-pushbuttons without doing the icon loading - as the 
Qt dialogs would have different icons on them compared to KDE dialogs. To see 
what I mean, just look at the printer dialog.

Craig.