QmlDesigner: Add model anchor functions to QmlAnchors

Change-Id: I50084cb28232ced2de8136b0e44efc4a14a28cc2
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>
QmlDesigner: Change resize handle to rectangle

Change-Id: Iffc08dda9dcb9260f72b07a492e93c40dfe59586
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>
QmlDesigner: Add AnchorIndicator

Change-Id: I0cd4b3c9dc0178936ffd96d8acb443ce1a228d1f
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>