Added method for relative correction retrieval.

src/libslic3r/SLAPrint.hpp

@@ -401,6 +401,9 @@ public:
     const SLAMaterialConfig&    material_config() const { return m_material_config; }
     const SLAPrintObjectConfig& default_object_config() const { return m_default_object_config; }
 
+    // Extracted value from the configuration objects
+    Vec3d relative_correction() const;
+
 	std::string         output_filename() const override;
 
     const SLAPrintStatistics&      print_statistics() const { return m_print_statistics; }