Cleanups:
- Rename "non-kpart" to "old style" (filename-based, doesn't support any child xmlguiclients)
- Rename "kpart" to "from [xmlgui]factory", since that's what this is really about
- Remove outdated comment about code that was causing 97572, seems Qt got smart enough to not
change the scroll position on the listview when we're clearing and re-filling it.