[NUI] Add markup extension methods for view properties

Add C# MarkUp Extension methods for View Properties.

e.g)
View myView = new ().Size(10f, 10f)
		    .Position(10f, 10f)
		    .Layout(new LienarLayout)
		    .Padding(5f, 5f, 5f, 5f)
		    .BackgroundColor(1f, 1f, 1f, 1f)

Added Properties

- Color
- ImageShadow
- Borderline
- Opacity
- Scale
- Visibility
- Sensitive
- IsEnabled
- ClippingMode
- Layout
- Focusable
- FocusableChildren
- FocusableInTouch
- VoiceInteractionName
- OffScreenRendering

and few getters for UI struct types.
- Color
- BorderlineColor