fix AreaPerimeterPolyline const name

lib/interfaces/process/items/types.dart

@@ -29,7 +29,7 @@ class MeasureTypes {
   static const String VolumeEllipse = "VolumeEllipse";
 
   /// 折线多边型测面积周长
-  static const String AreaPerimeterPolyline = "AreaPerimeterEllipse";
+  static const String AreaPerimeterPolyline = "AreaPerimeterPolyline";
 
   /// 前壁
   static const String AntCCA_IMT = "Ant.CCA IMT";