Auto color change: check overhangs lust from Preview when detecting auto color changes

+ fixed typo in equivalent_areas()
 + Added missed include

src/slic3r/GUI/DoubleSlider.hpp

@@ -31,7 +31,7 @@ constexpr double epsilon() { return 0.0011; }
 bool equivalent_areas(const double& bottom_area, const double& top_area);
 
 // return true if color change was detected
-bool check_color_change(PrintObject* object, size_t frst_layer_id, size_t layers_cnt,
+bool check_color_change(PrintObject* object, size_t frst_layer_id, size_t layers_cnt, bool check_overhangs,
                         // what to do with detected color change
                         // and return true when detection have to be desturbed
                         std::function<bool(Layer*)> break_condition);