Viewer of IsoFields is added

FieldVisualizer/Entities/Values/IValueRange.cs

@@ -0,0 +1,12 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace FieldVisualizer.Entities.Values
+{
+    public interface IValueRange
+    {
+        double TopValue { get; set; }
+        double BottomValue { get; set; }
+    }
+}