QmlDesigner: Use internal api for id in ModelNode

Change-Id: I73511fce451d90e9357b614655631377abf49b8c
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>
Reviewed-by: Marco Bubke <marco.bubke@digia.com>
QmlDesigner: Refactoring  ModelNode::setId

Add ModelNode::setIdWithoutRefactoring for changes without rewriter
interaction and change the rewriter to use it.
Rename ModelNode::setId to ModelNode::setIdWithRefactoring and add the
refactoring capabilities.

Change-Id: Ia5fba19bd2eeb034d525e92f39d30954e83fa747
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>
QmlDesigner: Refactor NavigatorTreeModel::handleChangedItem

Change-Id: I214b9a2c4ee751592e49eb0b7eba86c48c17c5a3
Reviewed-by: Marco Bubke <marco.bubke@digia.com>
QmlDesigner: InternalId is a signed integer

Change-Id: I511646de98f34d821b29a9fbbca88c2ff7401f3e
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>
QmlDesigner: Use the improved ModelNode::setId method

The exeception can only happen if the id is invalid which we test in
advance.

Change-Id: I867750495d656365004443351c15aa730326d566
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>