Sketcher Ellipse: code cleanup

deleting redundant overloaded functions involving arc-of-ellipse, a few
todo comments, not implemented methods, System(constraintlist)
constructor.

src/Mod/Sketcher/Gui/ViewProviderSketch.cpp

@@ -3951,7 +3951,6 @@ void ViewProviderSketch::rebuildConstraintsVisual(void)
             break;
             case InternalAlignment:
             {
-                // TODO: Implement visual representation (if any)
                 edit->vConstrType.push_back((*it)->Type);
             }
             break;