MMU segmentation refactoring: Most of the MMU segmentation code

was extracted to its own file.

src/libslic3r/MultiMaterialSegmentation.hpp

@@ -0,0 +1,18 @@
+#ifndef slic3r_MultiMaterialSegmentation_hpp_
+#define slic3r_MultiMaterialSegmentation_hpp_
+
+#include <utility>
+#include <vector>
+
+namespace Slic3r {
+
+
+class PrintObject;
+class ExPolygon;
+
+// Returns MMU segmentation based on painting in MMU segmentation gizmo
+std::vector<std::vector<std::pair<ExPolygon, size_t>>> multi_material_segmentation_by_painting(const PrintObject &print_object);
+
+} // namespace Slic3r
+
+#endif // slic3r_MultiMaterialSegmentation_hpp_