- Now properties can be escaped from the GetFullState() method that is
  used for the undo/redo state by providing an extra attribute inside
  xml proxy definition.

   <Proxy name="ComparativeViewBase">
      <DoubleVectorProperty name="ViewTime"
        command="SetViewTime"
        number_of_elements="1"
        state_ignored="1" <---------------------- NEW FLAG
        default_values="none">
        <DoubleRangeDomain name="range"/>
        <Documentation>
          The pipeline update time for this view.
          This gets passed to all representations added to this view.
        </Documentation>
      </DoubleVectorProperty>
   ...

- Some code clean up by removing the undo element used to create/delete proxy
  as well as the associated methods.

- Some debug code removed as well