Added CopyTo(Image/Texture) to NzRenderWindow

Added several methods to NzRenderer
Optimized NzRenderer::GetMax*();
Nz(Render)Window::GetSize now returns an unsigned vector
Fixed textures being flipped

include/Nazara/Utility/Window.hpp

@@ -61,7 +61,7 @@ class NAZARA_API NzWindow : NzNonCopyable
 		NzWindowHandle GetHandle() const;
 		unsigned int GetHeight() const;
 		NzVector2i GetPosition() const;
-		NzVector2i GetSize() const;
+		NzVector2ui GetSize() const;
 		NzString GetTitle() const;
 		unsigned int GetWidth() const;