com_sun_star_form_ORadioButtonModel_get_implementation ->
  com_sun_star_form_ORadioButtonControl_get_implementation

com_sun_star_form_OGroupBoxModel_get_implementation ->
  com_sun_star_form_OGroupBoxControl_get_implementation

and a bit of further cleanup.

Change-Id: I2d03d69ac83c482257baed5a6b84a6bacae68889