CppTools: Move setting category icon from Core to CppTools

This image is used exclusively in the CppTools plugin,
thus belong into CppTools resources.

Change-Id: I8bbc553fb16897b74487ad27a941776b83f14d77
Reviewed-by: Alessandro Portale <alessandro.portale@digia.com>
Debugger: Better handling of the tabbed extra views

Closing with the [x] now resets the Display mode of the associated
iname, and the view hides if there are no visible tabs left.
Also, remove the long-unused DisplayProcess format.

Change-Id: Ibd3308549af75e345c672c07f6714d26e7196e5a
Reviewed-by: Christian Stenger <christian.stenger@digia.com>