Graphics/RenderTechnique: Remove Clear method

Let's face it, this method was useless from the beginning.


Former-commit-id: c38f57785c900acf66560ad07aa29498312c6063

include/Nazara/Graphics/ForwardRenderTechnique.hpp

@@ -20,7 +20,6 @@ class NAZARA_API NzForwardRenderTechnique : public NzAbstractRenderTechnique
 		NzForwardRenderTechnique();
 		~NzForwardRenderTechnique() = default;
 
-		void Clear(const NzScene* scene) const override;
 		bool Draw(const NzScene* scene) const override;
 
 		unsigned int GetMaxLightPassPerObject() const;