QmlDesigner: Remove m_nodeHash from NavigatorTreeModel

Change-Id: I47d5e90ccd7e73daea755347e866d12355cabd20
Reviewed-by: Marco Bubke <marco.bubke@digia.com>
QmlDesigner: Cleanup the invisible code in the Navigator

Change-Id: Icc4ccbdc6090234cc9fc081786b2d80b9811ad16
Reviewed-by: Marco Bubke <marco.bubke@digia.com>
QmlDesigner: Exchange << with append

Change-Id: I4d0837e65f696c0909f3adfcd848bdc72d345463
Reviewed-by: Marco Bubke <marco.bubke@digia.com>