Implement clipping

[jsuarezruiz]

Implement clipping Views.

<alohakit:Rectangle
    WidthRequest="100" HeightRequest="100" 
    X="200" Y="0" 
    Fill="Red">
    <alohakit:Rectangle.Clip>
        <alohakit:EllipseGeometry 
            Center="50, 50"
            RadiusX="50"
            RadiusY="50"/>
    </alohakit:Rectangle.Clip>
</alohakit:Rectangle>