Graphics: Replace RenderFrame by RenderResources

This changes makes the whole rendering independent from the RenderFrame acquired from the Swapchain.
This may allow to do offscreen rendering (= without swapchain), or multi-window rendering in the future

include/Nazara/VulkanRenderer/VulkanRenderImage.inl

@@ -16,11 +16,6 @@ namespace Nz
 		return m_imageAvailableSemaphore;
 	}
 
-	inline UInt32 VulkanRenderImage::GetImageIndex()
-	{
-		return m_imageIndex;
-	}
-
 	inline Vk::Semaphore& VulkanRenderImage::GetRenderFinishedSemaphore()
 	{
 		return m_renderFinishedSemaphore;