Issue #844 Infinite filter problem after activating GEOM module : deactivateSelectionFilters is realized in displayer. When the module is deactivated, myAndFilter of displayer is removed from context, but the displayer has an instance, which is not in the context. So, the filters do not work after: NewGeom, Geom, NewGeom activating. We nullify this fillter on deactivation and it will be created and set to the context by the first get of this filter.
Issue #846 Color modification in preferences is applyed to the visualized objects after a model modification : correction to update the objects when "Default" state is clicked in the preferences dialog.
