Make JobItem::P_PROGRESS private

GUI/Models/JobItem.h

@@ -42,9 +42,9 @@ private:
     static const QString P_END_TIME;
     static const QString P_DURATION;
     static const QString P_COMMENTS;
+    static const QString P_PROGRESS;
 
 public:
-    static const QString P_PROGRESS;
     static const QString P_PRESENTATION_TYPE;
     static const QString T_SAMPLE;
     static const QString T_MATERIAL_CONTAINER;