- issue 2333: remove invalid sliders in a two pass process so as to not invalidate iterators       since a call to removeSlider already removed the slider from the list
- issue 2333: remove invalid sliders in a two pass process so as to not invalidate iterators
      since a call to removeSlider already removed the slider from the list

jonasfoe/COPASI,copasi/COPASI,copasi/COPASI,copasi/COPASI,copasi/COPASI,jonasfoe/COPASI,jonasfoe/COPASI,jonasfoe/COPASI,copasi/COPASI,jonasfoe/COPASI,jonasfoe/COPASI,jonasfoe/COPASI,copasi/COPASI,copasi/COPASI,jonasfoe/COPASI,copasi/COPASI,jonasfoe/COPASI,copasi/COPASI