Grid: function to reset to default %14.9f output format

src/tools/Grid.h

@@ -215,6 +215,8 @@ public:
   void projectOnLowDimension(double &val, std::vector<int> &varHigh, WeightBase* ptr2obj );
 /// set output format
   void setOutputFmt(const std::string & ss) {fmt_=ss;}
+/// reset output format to the default %14.9f format
+  void resetToDefaultOutputFmt() {fmt_="%14.9f";}
 /// Integrate the function calculated on the grid
   double integrate( std::vector<unsigned>& npoints );
 ///