Add Range Section (#120)

* Add Range Examples

* use var and cleanup

Source/Samples/Sections/Widgets/RangeSection.cs

@@ -0,0 +1,35 @@
+// This is free and unencumbered software released into the public domain.
+// Happy coding!!! - GtkSharp Team
+
+using Gtk;
+
+namespace Samples
+{
+    [Section(ContentType = typeof(Range), Category = Category.Widgets)]
+    class RangeSection : ListSection
+    {
+        public RangeSection()
+        {
+            AddItem(CreateHorizontalRange());
+            AddItem(CreateVerticalRange());
+        }
+
+        public (string, Widget) CreateHorizontalRange()
+        {
+            var adj = new Adjustment(0.0, 0.0, 101.0, 0.1, 1.0, 1.0);
+            var hScale = new HScale(adj);
+            hScale.SetSizeRequest(200, -1);
+            hScale.ValueChanged += (sender, e) => ApplicationOutput.WriteLine(sender, $"Value Change: {((HScale)sender).Value}");
+            return ("Horizontal", hScale);
+        }
+
+        public (string, Widget) CreateVerticalRange()
+        {
+            var adj = new Adjustment(0.0, 0.0, 101.0, 0.1, 1.0, 1.0);
+            var vScale = new VScale(adj);
+            vScale.SetSizeRequest(-1, 200);
+            vScale.ValueChanged += (sender, e) => ApplicationOutput.WriteLine(sender, $"Value Change: {((VScale)sender).Value}");
+            return ("Vertical", vScale);
+        }
+    }
+}