-setContainment, so that we don't have to try and use the parent any
more.
-hasConfigurationInterface; this should've already been there.
-default values for a couple of functions that I think make sense
svn path=/trunk/KDE/kdelibs/; revision=1012644
this is based off the wallpaper plugin. lots of copy&paste happened. the
dataengine code is still in there, just in case some plugin wants it
someday...
svn path=/trunk/KDE/kdelibs/; revision=1012635