QmlDesigner.PropertyEditor: Fix text alignment buttons

They have to use the new enum api.

Change-Id: Ib4ac7d56512007cb19fd7e6a65413198a9d90719
Reviewed-by: Alessandro Portale <alessandro.portale@digia.com>
QmlDesigner.PropertyEditor: Fix OriginControl

The control has to use the new enum api.

Change-Id: I73e86ac1c4f2c3fe4373b12968ac86fbbaee64aa
Reviewed-by: Alessandro Portale <alessandro.portale@digia.com>
QmlDesigner.PropertyEdior: Fixing ComboBox

If there is no enum value fall back to the instanced value.

Change-Id: Idd4654d6e9fb8d4afd3df0855861511bc06454c1
Reviewed-by: Alessandro Portale <alessandro.portale@digia.com>