- Updating visible section header frame computation

- Adding sections to the example project

ExampleProject/ConcordeExample/ExampleSectionHeaderView.h

@@ -0,0 +1,14 @@
+#import <Cocoa/Cocoa.h>
+
+#import "TUIKit.h"
+
+@interface ExampleSectionHeaderView : TUIView {
+  
+  TUITextRenderer * _labelRenderer;
+  
+}
+
+@property (readonly) TUITextRenderer  * labelRenderer;
+
+@end
+