Missing binding: RenderSurface::GetRenderBuffer/GetTarget

[andrekoehler]

I would like to use SkiaSharp to render with high performance into a RenderSurface. I see that the binding for RenderTarget offers "GetRenderTargetView" for Direct3D11 backends and "Surface" for Direct3D 9 backends (which are not supported by UrhoSharp as far as I know), but "GetRenderBuffer" or "GetTarget" are missing. These exist in the native Urho and are required to tell SkiaSharp where to render into.

[EgorBo]

Fixed in master, not sure why I marked those methods as OGL-only (probably they used to be so)