Rethought sla status indication.

src/libslic3r/SLAPrint.hpp

@@ -471,6 +471,15 @@ private:
     // Estimated print time, material consumed.
     SLAPrintStatistics                      m_print_statistics;
 
+    class StatusReporter {
+        double m_st = 0;
+    public:
+        void operator() (SLAPrint& p, double st, const std::string& msg,
+                         unsigned flags = SlicingStatus::DEFAULT);
+        double status() const { return m_st; }
+    } m_report_status;
+
+
 	friend SLAPrintObject;
 };