children list to avoid creating a gap between the ChoiceParameter and the Parameter created
     later in the QtGUI

ENH : backout changes in revision 6167f6fdbc74 and add the pointer needed in the QtParameterBase constructor

     - connect parameterBase slots to signal emitted from two checkbox,
       then two slots are available, one handling the signal related to a paremeter
       Group checkbox, and the other slot is relative to a simple parameter relative
      checkbox