QmlDesigmer.ItemLibrary: minor adjustment to layout

Change-Id: I444c342cb15473bfd65c3e2f364e285b21068319
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>
QmlDesigner.PropertyEditor: adjustment to layout of ItemPane

* Adding some space above the TabWidget
* Avoiding double black lines at the top

Change-Id: I0aedf151b548a665445d4219609738b2ab23c0be
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>
CppEditor: Fix build with namespaced Qt.

Change-Id: I30f872a57982c4de9fedec9c9e845bcf1fd0252b
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@digia.com>