SDLPP: add option to specify render object alignment

sdlpp/sdlpp_renderer.hpp

@@ -29,6 +29,8 @@ public:
 private:
     SDL_Renderer *renderer = NULL;
     bool render_coliders = false;
+    mutable Vec2D< int > dimensions_cache = { 0, 0 };
+    mutable Vec2D< double > double_dimensions_cache = { 0.0, 0.0 };
 };
 } // end of namespace SDLPP
 #endif