Make KFontAction mostly work -- at least enough for changing font in KolourPaint:

* Make changing the font in the GUI update the action (call i.e. setFont())

* Make programmatically calling setFont() update the GUI, but not fire a signal (mimicks KDE 3.5 behavior)

* Make createWidget() set the created combobox to the action's current font

This took a surprising amount of time to write (don't ask).