Moved Model::EnableDraw to SceneNode::EnableDrawing

Same goes for Model::IsDrawEnabled() => SceneNode::IsDrawingEnabled()
Is Drawable is now a pure virtual method from SceneNode


Former-commit-id: 217c6a21a98206ee0b283aaa216d419696a70faf

src/Nazara/Graphics/Light.cpp

@@ -171,6 +171,11 @@ NzColor NzLight::GetSpecularColor() const
 	return m_specularColor;
 }
 
+bool NzLight::IsDrawable() const
+{
+	return true;
+}
+
 void NzLight::SetAmbientColor(const NzColor& ambient)
 {
 	m_ambientColor = ambient;