SDLPP: Scene - add visitCollisions function

sdlpp/sdlpp_scene.cpp

@@ -107,6 +107,11 @@ Scene::getCollisions( RenderObject &r ) {
     }
     return ret;
 }
+void Scene::visitCollisions( RenderObject &r, Visitor &v ) {
+    for(auto &collision : getCollisions(r)) {
+        collision->visit(v);
+    }
+}
 std::vector< std::shared_ptr< RenderObject > >
 Scene::getCollisions( RenderObject &r,
                       const std::unordered_set< int > &objectIDs ) {