Get ride of the sidebar and use dockwidgets instead.

Get ride of the sidebar and use dockwidgets instead.
Default is now three panes, but the dockwidgets can be stacked, etc. to
the user convenience.

There's a slight loss in feature since I disabled dockwidgets hiding,
it's simply because some rework is still needed in kdelibs and Qt to
make them work correctly.

svn path=/trunk/playground/utils/dolphin/; revision=609186